Women Have a Hard(er) Time Losing Body Fat W/ Exercise 'cause it Increases Their Appetite More Than Men's, Right?

Is she going to binge after this body weight squat workout? Nah, don't worry...

I've repeatedly written about studies that show that the Taubs'ian notion that "exercise is useless because it just makes you hungry" is bullsh*t. It is indeed useless to work out to burn calories, it is yet never useless to work out - even if fat loss, not health or longevity is your goal.

What you should be aware of, though, is that there is a gender bias in the selecting of subjects in health sciences; and since the average subject in nutrition and exercise sciences is male and studies that have enough male and female subjects to identify relevant sex differences are rare, we don't really know if everything that has been "scientifically proven" can also be considered "scientifically proven" for female dieters and/or trainees.

Learn more about the (often ;-) small but significant difference at the SuppVersity

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The effects exercise will have on your appetite, for example, is such a research interest that has been investigated mainly in male subjects. As Alice E. Thackray, et al. (2016) point out in their latest paper in Nutrients, ...

"[...] opportunities to examine sex-based differences have been limited, but represent an interesting avenue of inquiry considering postulations that men experience greater weight loss after exercise interventions than women" (Thackray, 2016). 

In other words: While we don't know much, the few things we do know about the sex-specific interaction between exercise and your appetite are enough to draw a handful of practically highly relevant conclusions about optimal exercise and diet regimens for women.

Acute exercise, appetite, and compensation with energy intake - it's primarily individual

Before we delve deeper into sex-differences, though, I would like to remind you that the individual differences in fat and weight loss are not just better studied than those between men and women, they are probably also much more relevant than any sex difference - and that in spite of the fact that the research suggests that they are mediated by the same (individual) differences in compensatory behaviours that negate the exercise-induced energy deficit as the inter-individual differences.

Figure 1: The 2008 study by King et al. shows that (a) the individual differences in appetite are magnitudes larger than the actual effect of exercise and that (b) what the subjects make of it in terms of their effects on the subjects' actual energy intake cannot be predicted based on these subjective changes (King. 2008).

In their 2008 study, for example, King et al. found that the individual propensity to compensate for a reduction in energy intake and/or an increase in expenditure can explain weight loss differences that are larger than 50% - albeit with a standard deviation in the "compensators" that is significantly larger than the total weight loss.

SuppVersity Suggested Article: "Training "On Cycle", Done Right - Women See Much Better Results When Periodization is in Line W/ Menstrual Cycle" | read it

Did you know that women benefit from dieting and training in-sync with their menstrual cycle? I am pretty sure you know that as I've mentioned this before at the SuppVersity and even wrote a whole article about "Training on the Female Cycle"evidence  suggests that compared with untailored programs, synchronising diet and exercise training interventions around the hormonal changes that occur during the menstrual cycle elicits greater weight loss (Geiker, 2016) and improvements in muscle strength (learn more). Yet while we do know how cyclical fluctuations in sex hormones (estrogen and progesterone) alter appetite-regulatory hormone concentrations and energy intake in women (Buffenstein, 1995; Brennan, 2009), however, we don't know their interaction with exercise.

Similar discrepancies were found for the effect on subjective hunger, where the standard deviation of the subjects' hunger on a visual analog scale was ±9.6 mm and thus 240x larger than the average appetite increase of 0.4 mm/day. That's huge and it's quite a pity that the study didn't have enough subjects to conduct a meaningful analysis of the effect of the interactions of the subjects' sex on the increase in hunger the subjects experienced in King's 12-week study over the course of which the subjects trained five times a week without having to adhere to an energy restricted diet.

Men or women - that could still make an important difference

That this analysis could have yielded a significant difference between men and women, however, appears to be refuted by studies like Alajmi, et al. whose healthy male and female subjects had - within the previously described inter-individual differences - identical changes in the concentrations of the hunger-regulating acetylated form of ghrelin in response to 60 min treadmill running at 70% VO2peak (see Figure 2) - and that even though the men burned 57% more energy than the women.

Figure 2: Time-averaged total area under the curve (AUC) for appetite ratings (left); and plasma acylated ghrelin concentrations (right) in the control trial (□), and after 60 minutes on the treadmill at 70% VO2peak (■) in Alajmi's study.

In fact, the data in Figure 2 appears to confirm - for both men and women - the anorexic effect that is often ascribed to exercise. The study by Alajmi et al. is yet only one out of four partly contradictory studies that investigate the sex-based differences in the regulation of appetite in response to acute exercise:

• Kawano, et al. (2012) - The first acute exercise and appetite study that compared men and women was published in Obesity Research & Clinical Practice. The authors reported that 20 min of rope skipping exercise increased ratings of subjective hunger 30 min after exercise in women but not men - quite a surprising result, also because high(er) intensity exercise as rope skipping has been shown to be particularly appetite suppressive in the average (=male) study subject; furthermore, Thackray et al. rightly criticize that the authors did not "control for the potential confounding effects of the menstrual cycle, which represents an important consideration for acute exercise studies comparing men and women" (Thackray. 2016). In this regard, recent studies have given us a few interesting insights (see light blue box). However, whether appetite responses to exercise in women are influenced by the menstrual cycle phase is not known and "represents", as Thackray et al. write "a research avenue to consider in the future".
• Hagobian, et al. (2012) - Scientists from the California Polytechnic State University tested the effects on both appetite and energy intake in 11 men and 10 women exercised for 60 min on a cycle ergometer at 70% VO2peak until 30% of total daily energy expenditure was expended (men, expenditure = 975 ± 195 kcal in 82 ± 13 min; women, expenditure = 713 ± 86 kcal in 84 ± 17 min) in a counterbalanced, crossover study.
  

  

  Figure 2: Energy intake (see captions) and macronutrient composition (graph shows %-ages, the figures indicate the actual intake in g) of the post-workout ad-libitum meal (Hagobian, 2012).

  In line with Alajmi et al. (2012) and in contrast to Kawano et al. (2012), Hagobian et al. (2012) found a sign. reduction in energy intake (P < 0.05) after exercise compared with rest in men (672 ± 827, 1133 ± 619 kcal, respectively) and women (−121 ± 243, 530 ± 233 kcal, respectively). A result the scientists interpret as evidence of the previously cited "effectiveness of acute exercise to suppress relative energy intake regardless of sex" (Hagobian, 2012).
• Bailey, et al (2015) - While the previous studies tested relative intense steady state exercises, a 2015 study from the University of Bedfordshire focused on a very different type of exercise. In fact, the 'exercise intervention' consisting of walking a total of 28 min in form of 2 min bouts every 20 minutes was designed to investigate the effect of daily physical activity on appetite and energy intake in 6 male and 7 female inactive, but otherwise healthy subjects, whose appetite and appetite-regulatory hormones were not affected by the exercise intervention.

You probably already suspect it: intensity is a key regulator of the effects of exercise on subjective appetite, but since I've addressed that before while discussing the sex-differences only superficially, I want to refer you to my previous article and focus on the influence of sex of which separate studies in men and women, respectively appear to suggest that...

• 24h energy intake is unchanged in both, men and women in the few studies that investigated this important parameter in male and female subjects in isolation
• acute energy intake (post exercise) mostly remains the same, often decreases and rarely increases in men and women when studied in isolation
• exercise intensity, that's what evidence suggests modulates the effects on energy intake for both, men and women; in that, low-intensity exercise such as walking appears to be more prone to increase energy intake than high(er) intensity exercise such as jogging or sprinting
• dietary overcompensation, i.e. an extra energy intake that provided more energy than the subjects had burned during their workouts, does not occur in either men nor women
• individuality reduce the validity of the results; as previously pointed out, the appetite response to exercise appears to be highly individual and whether that's due to genetics and/or baseline diet (e.g. low carb vs. low fat, etc.) will have to elucidated in the future 

The one thing that's still left to discuss is the chronic effect of exercise on appetite, hunger, the respective hormones and - most importantly - men's and women's energy intakes.

The effects of chronic exercise

Unfortunately, studies that compared the effects of chronic exercise on appetite and food intake of men and women directly, don't exist. What we do have, though, are studies on both men and women (not adequately powered for comparisons), as well as studies that investigate men and women in isolation. These studies suggest that...

• complex interactions w/ weight loss in both men and women - If weight loss occurs in response to chronic exercise, that's, according to King, et al. (2009), because overweight individuals (men and women) balance any potentially existing increased drive to eat due to the extra energy expenditure with a concomitant increase in the satiety response to a meal (increased insulin sensitivity, decreased acetylated ghrelin, decreased leptin | Martins. 2010 & 2013).
  
  Similarly, Thackray et al. conclude in their previously cited review that this interactive effect between exercise, weight loss and appetite / energy intake also explain the complex alterations in appetite-regulatory hormones, of which they even go so far as to say that they "arise as a secondary consequence to changes in body mass" (Thackray, 2016)
• overall, women are more susceptible to changes in energy balance - In the long-term, it becomes more apparent that women react more sensitive to changes in their energy balance. Comparing studies in men and women (direct comparisons don't exist) suggest that this is why women are more susceptible to perturbations in appetite-regulatory hormones and energy intake.
• exercise is less likely to trigger dietary compensation than energy restriction - In contrast to the initially referenced statement of Gary Taubes, it's dieting that makes you hungry, not exercise in both men (King, 2011) and women (Alajmi, 2016). "Dietary restriction," Thackray et al. explain may simply "represent a greater challenge to appetite regulation and energy balance than exercise".
  
  

  

  Figure 3: The energy intake between men and women differed in a 12-week aerobic exercise training intervention in overweight and obese men (n = 35) and women (n = 72), but the effect on the objectively measured (quantified using laboratory-based test meal days) did not differ between the male and female subjects (Caudwell, 2013)..

  And since we know that women react more sensitive to changes in said energy balance, it is not exactly surprising that individual two separate studies by Stubbs et al. (2002a,b) show that only women will compensate ~33% of the extra energy they expended during seven days of daily moderate- or high-intensity exercise (Stubbs, 2002a), while men didn't change their energy intake, at all (Stubbs, 2002b) - at least if we trust their food logs and the subjects' own scales, because that's what Stubbs et al. used as their data source.
  
  That's a problem, because - as usual - other studies suggest an increased compensation in men or, just as one of the few tightly controlled studies in this field no sex- but sign. indiv. differences (Caudwell, 2013). 

Eventually, the jury is thus still out. While anecdotal evidence suggests and evolutionary considerations, i.e. "that women have evolved to store body fat to preserve energy balance and reproductive function" (Thackray, 2016), could even explain an increased energy expenditure in women, the hard evidence we'd need for a definitive conclusion is simply not there.

Not Exercise, But Dieting Makes You Hungry: Beneficial or No Effects on Appetite of Exercise in Lean & Obese. (Ab-) using Exercise to Make Up For Messy Diets Still a Bad Idea! More...

Don't complain, ladies. Use your energy in the gym! As Thackray et al. point out, most of the more recent experimental work "question[s] the prevailing view that exercise is less effective for inducing weight loss in women, with several studies showing equivalent effects of exercise training on body composition in both sexes when the exercise-induced energy expenditure is matched" (Thackray, 2016) - the latter is obviously rarely the case, after all, women have a lower body weight and a lower lean body mass. So even if they trained at the same intensity as men (which a comparison of the average male to the average female gym-goer suggests they don't), they still wouldn't burn as much energy...

Rather than to complain about how unfair life is when it comes to exercise and fat loss, women should use their energy in the gym and focus on the new research on how training and eating according to their menstrual cycle could augment both, their exercise-induced fat loss and the actually desired changes in body composition | Comment on Facebook!

References:

• Bailey, Daniel P., et al. "Breaking up prolonged sitting time with walking does not affect appetite or gut hormone concentrations but does induce an energy deficit and suppresses postprandial glycaemia in sedentary adults." Applied Physiology, Nutrition, and Metabolism 41.3 (2015): 324-331.
• Brennan, Ixchel M., et al. "Effects of the phases of the menstrual cycle on gastric emptying, glycemia, plasma GLP-1 and insulin, and energy intake in healthy lean women." American Journal of Physiology-Gastrointestinal and Liver Physiology 297.3 (2009): G602-G610.
• Buffenstein, Rochelle, et al. "Food intake and the menstrual cycle: a retrospective analysis, with implications for appetite research." Physiology & behavior 58.6 (1995): 1067-1077.
• Caudwell, Phillipa, et al. "No sex difference in body fat in response to supervised and measured exercise." Medicine & Science in Sports & Exercise 45.2 (2013): 351-358.
• Geiker, Nina RW, et al. "A weight-loss program adapted to the menstrual cycle increases weight loss in healthy, overweight, premenopausal women: a 6-mo randomized controlled trial." The American journal of clinical nutrition (2016): ajcn126565.
• Hagobian, Todd Alan, et al. "Effects of acute exercise on appetite hormones and ad libitum energy intake in men and women." Applied Physiology, Nutrition, and Metabolism 38.999 (2012): 66-72.
• Kawano, Hiroshi, et al. "Appetite after rope skipping may differ between males and females." Obesity research & clinical practice 6.2 (2012): e121-e127.
• King, Neil A., et al. "Individual variability following 12 weeks of supervised exercise: identification and characterization of compensation for exercise-induced weight loss." International Journal of Obesity 32.1 (2008): 177-184.
• King, Neil A., et al. "Dual-process action of exercise on appetite control: increase in orexigenic drive but improvement in meal-induced satiety." The American journal of clinical nutrition 90.4 (2009): 921-927.
• King, James A., et al. "Differential acylated ghrelin, peptide YY3–36, appetite, and food intake responses to equivalent energy deficits created by exercise and food restriction." The Journal of Clinical Endocrinology & Metabolism 96.4 (2011): 1114-1121.
• Martins, Cecilia, et al. "The effects of exercise-induced weight loss on appetite-related peptides and motivation to eat." The Journal of Clinical Endocrinology & Metabolism 95.4 (2010): 1609-1616.
• Martins, Catia, et al. "Effect of chronic exercise on appetite control in overweight and obese individuals." Medicine and science in sports and exercise 45.5 (2013): 805-812.
• Stubbs, R. James, et al. "The effect of graded levels of exercise on energy intake and balance in free-living men, consuming their normal diet." European journal of clinical nutrition 56 (2002a): 129-140.
• Stubbs, R. James, et al. "The effect of graded levels of exercise on energy intake and balance in free-living men, consuming their normal diet." European journal of clinical nutrition 56 (2002b): 129-140.

Is Intensity the Key to Minimize Exercise Induced Cravings? What About Workout Duration? What About Sex Differences - Are Women Hungrier Than Men After Workouts?

Next to intensity and duration, sex may be an issue, as well.

On the one hand, you have Dr. Oz and other mainstream sources who say: "Exercise is the key to weight loss! You just make sure you burn an adequate amount of energy everyday and the belly will be gone sooner or later." On the other hand, you will see people like Gary Taubes say: "Whut? Beware of exercise! It's only going to make you hungry!"

A true dilemma! Specifically in view of the fact that both of them can cite studies to support their claims.

If we approach the question a bit less dogmatically, however, it will soon become obvious that neither Oz nor Taubes are "right" or "wrong". Why? Because, as usual, the subject is more complex than the "exercise yes / no" dogma suggests.

Learn more about factors that influence appetite here at the SuppVersity

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You can't "out-exercise" a sloppy diet - don't even try | learn why.

In general, Oz is certainly right: For weight loss to occur, a sustained negative energy balance is required and is typically achieved by decreasing energy intake (i.e. dieting) and/or increasing energy expenditure (i.e. exercising).

Taubes, on the other hand, makes a valid point: In the real world, an increase in energy expenditure is often compensated for by an increase in energy intake.

The optimal exercise regimen would thus be one that burns a hell lot of exercise without having significant effects on the appetite of its practitioners. In today's SuppVersity article we are going to take a look at exercise variables that may influence the effect on appetite, in order to identify the "optimal exercise regimen".

Duration & intensity matter! The longer, the hungrier. The harder, the more satiated?

In one of the most comprehensive studies to date, Erdmann et al. observed in a combined sample
of normal-weight men and women that cycling for only 30 min cycling at either 50 or 100 W had no effect on subsequent appetite ratings and energy intake.

Figure 1: Effects of exercise duration and intensity on energy intake; exemplary study results
from Erdmann et al. (2007, left) and Larson-Meyer et al. (2012, right)

After 120 minutes of cycling at a fixed work rate of 50 W, on the other hand, lead to significant increases in energy intake. The problem with Erdmann's study is yet that it was conducted first thing in the morning after an overnight fast. In a "fed" scenario the impact of the exercise duration may have been more significant.

Likewise, not 100% beyond doubt are the results Larson-Meyer et al. (2012) presented in a 2012 study, the results of which would suggest that working out at lower intensities will have, while working out in the "fat burning zone" of ~70% VO2 max won't have significant effects on post-workout (2h) energy intake.

Methodological problem #1: Measuring only post-workout intake is a shortcoming of the majority of studies. Providing an ad-libitum meal exactly 10 min after exercise completion, as it was done by Westerterp-Plantenga (1997) or Almada et al. (2013), for example, leaves more then enough room for an evening binge that would annihilate the benefits of any post-workout anorexic effects of exercise.

As Deighton & Stensel point out in a recent review (2014), it is however "plausible that the higher percentage body fat and lower VO2 max in the walking group may have confounded the results." In fact, a study by Finlayson et al. demonstrated that body fat and physical activity levels may influence the energy intake response to exercise - at least in females.

The unfitter + fatter, the hungrier! At least in women!?

The scientists from the Institute of Psychological Sciences at University of Leeds analysed the energy intake response to 50 min cycling exercise and separated the participants into two groups: C
ompensators and non-compensators.

Figure 2: Men and women may react differently to exercise; specifically, in men the association between obesity + activity levels and post-workout binges is less pronounced (Finlayson. 2009; Jokisch. 2012)

Compensators were defined as the participants that increased energy intake beyond the energy cost of exercise, whereas non-compensators consumed less energy than that expended during exercise. Analysis of between-group differences revealed a significantly higher BMI and percentage body fat and a lower habitual exercise frequency in the compensators.

What is interesting, though, is that Jokisch et al. were not able to reproduce these results in a recent study with male subjects who exercised for 45 min at 65–75 % of the maximum heart rate and did not respond according to their body fat / weight levels.

Remember? You've learned in previous articles that obese men listed mainly protein/fat sources (meat dishes) among their favorite foods, obese women tended to list predominantly carbohydrate/fat sources (doughnuts, cookies, cake) and foods that were sweet (Drewnowski. 1992). This desire for sugar will be specifically pronounced in unfit women who will burn more glucose than fat during their workouts and could thus partly explain the sex difference observed in the Finlayson study.

Yet even if we assume that obese women run the risk of overeating after workouts. Deighton and Stensel, whose review I referenced previously in this article, were unable to find a single study, where the post-exercise increase in energy intake exceeded the amount of energy that was expended.

The ‘relative energy intake’ is always negative

Or put simply, if the women expend 400kcal per workout and eat 1200kcal instead of 1000kcal on the subsequent meals, they will still have a net deficit of 200kcal.

Table 1: Energy intake during the control and exercise trials of a study investigating the long(er) term effects of exercise on energy intake (King. 2010)

This is particularly relevant, since current evidence suggests that exercise, alone (we are not talking about dieting + exercise, here) won't effect the 24+ energy intake of nine healthy men, who ran for 90 min at  68.8± 0.8% of maximum oxygen uptake  followed by 8.5 h of rest (King. 2010).

Similar effects, ... or rather no effects have been observed by Hanlon et al (2012). for a 24 h period in obese and non-obese women King et al. (1997) in a study on free-living men which analyzed a time-period of 48h, and Pomerleau (2004) in physically active women over a time-period of 72h.

Bottom line: The Taubsian notion that exercise would promote overeating is thus probably incorrect. Whether one mode of exercise is better than the other, however, is still in the open. The currently available evidence gravitates towards shorter exercise durations and medium-to-high intensities.

More Than 3x Higher EPOC Induced Energy Expenditure W/HIIT vs. LISS! Read more in a previous article!

However, even if the casual walk with the dog will have you compensate for the increased energy expenditure on the next occasion. There is no evidence that this increase is going to increase your relative energy intake. In view of the non-weight loss related benefits of exercise it would thus be stupid to stop walking the dog or doing your regular aerobics.

What really counts is (a) that you exercise regularly (3x per week+) and (b) understand that exercise can promote, yet not drive weight loss: To build abs you got to train, to make them visible you got to diet  | Comment on Facebook!

Reference:

• Deighton, Kevin, and David J. Stensel. "Creating an acute energy deficit without stimulating compensatory increases in appetite: is there an optimal exercise protocol?." Proceedings of the Nutrition Society 73.02 (2014): 352-358.
• Drewnowski, Adam, et al. "Food preferences in human obesity: carbohydrates versus fats." Appetite 18.3 (1992): 207-221.
• Erdmann, Johannes, et al. "Plasma ghrelin levels during exercise—effects of intensity and duration." Regulatory peptides 143.1 (2007): 127-135.
• Finlayson, Graham, et al. "Acute compensatory eating following exercise is associated with implicit hedonic wanting for food." Physiology & behavior 97.1 (2009): 62-67. 
• Hanlon, Bliss, et al. "Neural response to pictures of food after exercise in normal-weight and obese women." Medicine and science in sports and exercise 44.10 (2012): 1864-1870.
• Jokisch, Emily, Adriana Coletta, and Hollie A. Raynor. "Acute energy compensation and macronutrient intake following exercise in active and inactive males who are normal weight." Appetite 58.2 (2012): 722-729. 
• King, N. A., et al. "High dose exercise does not increase hunger or energy intake in free living males." European journal of clinical nutrition 51.7 (1997): 478-483.
• King, James A., et al. "Influence of prolonged treadmill running on appetite, energy intake and circulating concentrations of acylated ghrelin." Appetite 54.3 (2010): 492-498.
• Larson-Meyer, D. Enette, et al. "Influence of running and walking on hormonal regulators of appetite in women." Journal of obesity 2012 (2012).
• Pomerleau, Marjorie, et al. "Effects of exercise intensity on food intake and appetite in women." The American journal of clinical nutrition 80.5 (2004): 1230-1236.

Ramadan Improves Body Composition of Young & Older Men, Young Women Don't Benefit and Women >37y Become Fat During the Fast - Implications for Intermittent Fasting?

It may not be "paleo conform", there but the traditional Ramadan menu is 100% home-made from fresh foods - that alone will make a huge difference.

"I hear you..." What's that supposed to mean? Well, in a way I am running the SuppVersity for me, because I like the idea that people like you come here and think "Hey, today I've learned something new", "... read something interesting" or at even"... have been enlightened". On the other hand, this entails that I got to tailor the topics to your interests as well and since the short Facebook item on the effects of Ramadan fasting on body composition I posted on Facebook, a couple of days ago, which spiked so much interest, I will take it up and write a whole article about this soon-to-be-published study from the Mashhad University of Medical Science and the University of Nicosia (Norouzy. 2013).

Ramadan is not "intermittent fasting"...

... at least not in the sense it's interpreted by most people.In fact, there are a whole host of differences one could think about, but for our purpose which is the use of intermittent fasting as a way to live healthier and/or improve our physique these are just a couple of examples that come to mind:

• 

  Effect of Ramadan fasting on perceived snack, fluid and food intake in 411 male and 323 female Malaysian Junior Level Muslim athletes (data calculated based on Singh. 2011; originally posted as part of the Intermittent Thoughts on Intermittent Fasting on Sept. 06, 2011)

  The fasting window can actually be pretty small - While all Muslims will eat the lions-share of their energy intake in the evening many rise early (esp. when Ramadan falls into the winter months) and ingest a medium sized breakfast to "make it through the day".
• Food quality (from a health perspective) is not always ideal - While researchers have observed that there seems to be an unconcious increase in protein intake (+6.6% protein; less carbs and fats; Trabelsi. 2011), this is yet not a characteristic feature of the protocol, but rather a result of dining with the family, not snacking and putting an emphasis on whole self-prepared (and more expensive) food.
  
• During the fast Muslims don't drink - This is obviously something anybody following a "lean gains" like intermittent fast or an "alternative day fasting" protocol, where people eat only 500kcal or so two or three times a week and just follow their habitual diet on the other days would not remotely consider. However, in a paper published in the European Journal of Clinical Nutrition in 2003, Leiper, Molla and Molla report that despite the fact that "[d]uring the daylight hours of Ramadan fasting, practising Muslims are undoubtedly dehydrating", it is neither "clear whether they are chronically hypohydrated" nor have there been any "detrimental effects on health [...] directly attribut[able] to negative water balance at the levels that may be produced during Ramadan" observed in any scientifically relevant studies (Leiper. 2003). It is thus relatively safe for us to assume that we can neglect he influence of potential dehydration in our initial analysis of respective studies.
• Other differences  - I guess, I better spend time discussing the latest study and refer you to the Intermittent Thoughts Series, where I discussed the existing differences and implication at length. You can browse the articles here. Start with the first post "Myth #1: A Higher Meal Frequency Equals a Higher Metabolic Rate" from September 4th, 2011 and click yourself through the  rest of the series. You won't regret reading it, I promise ;-)

A one-to-one translation of the results from the study at hand to your efforts of a practical and effective way to lose body fat (this is where it excels - and not in "lean gaining") is thus unwarranted. There may yet still be a couple of things, we can learn from what the observations the Iranian and Greek researchers made in their 240 adult subjects (male: 158) who fasted between sunrise and sunset for at least 20 days.

Figure 1: Body weight and composition before and after Ramadan and percentage changes from baseline according to gender and age; data expressed relative to baseline (Norouzy. 2013)

As the data in figure 1 goes to show you the overall pattern that emerges is positive one. However, the weight the subjects, who were grouped according to age and sex, lost was (as it was to be expected, by the way) not pure fat mass. Still, with the exception of older women all subjects improved their body fat levels.

Is intermittent fasting not for women?

Apropos women, it's not just that the older women (>37y) did actually gain body fat, the already minimal reduction in body fat (%) in the younger women was also non-significant (p = 0.079 vs. p=0.029 in men). Taken together these results appear to suggest that a non-controlled, intermittent fasting regimen that's based solely on the absence of food intake in the course of the day would be beneficial for men only.

Looks good, tastes good, is good - high protein foods! Unfortunately many  women (obyiously not you, right) have still not gotten the message that by simply making sure you have 30g+ of protein in your three-square meals is probably the easiest way to improve both your physique and health. Still, the study at hand provides further evidence that a low protein intake is not all that makes it more difficult for women to lose fat (learn more)

It should be said, though, that these results stand in conflict with previous studies by Husain et al. who report more, not less weight and body fat loss in the 20-45 year-old female subjects of their Ramadan fasting study (Husain. 1987). An observation they pin on the "increase in energy expenditure" that comes with preparing the meal for the whole family... well, you know that I am not afraid of calling *bs* by its name and this explanation certainly is*bs*. It is in fact much more likely that the differences could be explained by a lower overall energy intake just as the increase in body weight Frost & Pirani observed in the young men in another cohort was solely a result of the nightly binges (Frost. 1987). I mean, we all know that women are more likely to be concerned about the detrimental effects of a high food intake in the evening on their body composition, so that it is not unlikely that the 20-45 year old women in the Husain study were deliberately limiting their energy intake, while the men in the study by Frost & Pirani gave in to their ravenous appetite and the delicious meals their wifes, sisters and aunts had prepared (I will leave it up to you if you call the role allocation "traditional" or "chauvinist", btw. ;-)

This is basically also how Norouzy et al. try to explain the inconsistencies that become obvious, when you compare the study at hand to previous results:

"This inconsistency may be a result of the subject characteristics and, in particular, age, sex and physical activity, as well as the number of hours of fasting observed during Ramadan, which varies according to geographical location from 11 to 19 h a day." (Norouzy. 2013)

Furthermore, the majority of previous studies included young subjects aged <35 years; thus, limited information is available on subjects of older ages and according to Norouzy et al. their study was the first to "attempted to compare changes in body weight and composition in different ages and sex" (Norouzy. 2013). In view of the existing differences in resting energy expenditure and physical activity this could well explain part of the differences between the studies and the high amounts of "null results" (=no change at all) other scientists reported (Ati.1995; Finch. 1998; Ramadan. 2002; Yucel.2004).

Figure 2: Dietary energy, macronutrient and fibre intakes before and during Ramadan and percentage changes from baseline according to gender; I must warn you though, according to the scientists dietary records were not available from all participants (Norouzy. 2013)

Going back to the study at hand, the data in figure 2 indicates that neither the general trends, nor the age and sex-specific differences can be fully explained by changes in total energy (due to high variability borderline significant only in men, totally insignificant in women) or macronutrient ratios (insignificant in both); an observation the Iranian researchers try to explain by differences in nutrient oxidation and changes in energy expenditure during the fasting period and add:

Overtraining and undereating will have your thyroid hormones plummet within no more than four days (learn more) - would Intermittent Fasting make that worse, or could it - as I suggest in the bottom line - maybe even postpone the onset of plummeting T3 and increasing rT3 levels by allowing you to eat to satiety once a day? Respective studies are missing, but it does not sound totally implausible!?

"A previous study investigating the effect of Ramadan on the abdominal fat distribution by computed tomography found reductions only in the visceral fat tissue area, and only in subjects in their twenties and in women, and attributed this to fat redistribution because no changes in weight were observed (Yucel et al., 2004). Thus, although this remains to be investigated, differences between sexes and ages may be a result of differences in nutrient oxidation and changes in energy expenditure during the fasting period. For example, as shown in healthy women aged 25–39 years, Ramadan fasting induced a significant decline in carbohydrate oxidation and a significant increase of fat oxidation, as well as a decline in diurnal energy expenditure, which may be attributed to the absence of post-prandial thermogenesis during fasting (Ati al., 1995). A reduction of energy expenditure during Ramadan was also reported in another study (Sweileh et al., 1992)." (Norouzy. 2013)

Now, these changes in (1) fatty acid oxidation (Ati. 1995), (2) improvements in visceral fat (questionable whether those occurred in the study at hand that did not observe sign. reductions in waist circumference in any group) and (3) overall energy expenditure would unquestionably be of interested for the average physical culturist, as well and (1) could in fact be one of the reasons that numerous people report great fat loss following respective regimen. After all, one of the major obstacles of translating fatty acid oxidation to fat loss is that the latter must occur in the presence of an energy deficit or the body fat that's getting oxidized on time-point T1 is going to be replenished from the fats, carbs and protein on time-point T2.

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Exercise prevents, not amplifies, fasting induced protein degradation. In a 2006 paper, Kasperek et al. report that

"Exercise did prevent the increase in the rate of total protein degradation caused by food restriction, which may have important implications in weight reduction diets." (Kasperek. 2006)

And indeed, any type of fast (even an intermittent one) that is intended to improve body composition would be missing out big time without the exercise component - just keep it to a sane level and focus on muscle preserving strength training.

Energy intake counts: If you remember the recent SuppVersity post on the detrimental effects a caloric deficit can have on the thyroid function in the presence of a high volume training regimen after four days only, it may sound hilarious that the bottom line starts with the words "energy intake counts". However, faced with the fact that a very large energy deficit will stall weight loss, people tend to forget that not being in a minimal energy deficit won't allow you to lose weight either (the whole alternate day fasting regimen is based on the simple fact that 90% of the people won't fully compensate for the caloric deficit on the low calorie = fasting days).

In that intermittent fasting or rather the ingestion of one or two large meals instead of many mini-meals may provide an edge over "classic" dieting as it allows for a daily "feast" that could trick your body to believe that the starvation it experienced earlier in the day was already over. This in turn could delay the metabolic slowdown and rock bottom T3 levels Loucks et al. observed in the female participants of their exercise + dieting trial within no more than 4 days (go back and learn all the details about the Loucks study). If that's the case, we would not have an absolute increase in energy expenditure (see pt. 3, above), but at least a relative one - compared to eating 6 mini square meals.

References:

• el Ati J, Beji C, Danguir J. Increased fat oxidation during Ramadan fasting in healthy women: an adaptative mechanism for body-weight maintenance. Am J Clin Nutr. 1995 Aug;62(2):302-7.  
• Frost G, Pirani S. Meal frequency and nutritional intake during Ramadan: a pilot study. Hum Nutr Appl Nutr. 1987 Feb;41(1):47-50.
• Husain R, Duncan MT, Cheah SH, Ch'ng SL. Effects of fasting in Ramadan on tropical Asiatic Moslems. Br J Nutr. 1987 Jul;58(1):41-8.
• Kasperek GJ, Conway GR, Krayeski DS, Lohne JJ. A reexamination of the effect of exercise on rate of muscle protein degradation. Am J Physiol. 1992 Dec;263(6 Pt 1):E1144-50. 
• Leiper JB, Molla AM, Molla AM. Effects on health of fluid restriction during fasting in Ramadan. Eur J Clin Nutr. 2003 Dec;57 Suppl 2:S30-8.
• Ramadan J. Does fasting during Ramadan alter body composition, blood constituents and physical performance? Med Princ Pract. 2002;11 Suppl 2:41-6. 
• Singh R, Hwa OC, Roy J, Jin CW, Ismail SM, Lan MF, Hiong LL, Aziz AR. Subjective Perception of Sports Performance, Training, Sleep and Dietary Patterns of Malaysian Junior Muslim Athletes during Ramadan Intermittent Fasting. Asian J Sports Med. 2011 Sep;2(3):167-76.
• Sweileh N, Schnitzler A, Hunter GR, Davis B. Body composition and energy metabolism in resting and exercising muslims during Ramadan fast. J Sports Med Phys Fitness. 1992 Jun;32(2):156-63. 
• Trabelsi K, El Abed K, Trepanowski JF, Stannard SR, Ghlissi Z, Ghozzi H, Masmoudi L, Jammoussi K, Hakim A. Effects of ramadan fasting on biochemical and anthropometric parameters in physically active men. Asian J Sports Med. 2011 Sep;2(3):134-44.
• Yucel A, Degirmenci B, Acar M, Albayrak R, Haktanir A. The effect of fasting month of Ramadan on the abdominal fat distribution: assessment by computed tomography. Tohoku J Exp Med. 2004 Nov;204(3):179-87.

Cardio & Strength Training in a Single Workout: "What Do I Do First?" Plus: Could the Answer Be Sex-Specific?

"Men are different women, too..." We all know that, but can we still train together or will women have to do cardio first, while men would be better off starting out lifting weights?

This is not the first and certainly not the last article on what should come first, if you actually have to or want to do endurance and resistance training in single workout session. Today's SuppVersity article is however the one on the study with the most detailed evaluation of the differential effects of "endurance vs. resistance training first" on the endocrine response, neuromuscular fatigue and power in men and women, I have seen in a while. The pertinent paper is titled "Acute Hormonal and Force Responses to Combined Strength and Endurance Loadings in Men and Women: The 'Order Effect'" and has been written by Ritva S. Taipale and Keijo Häkkinen from the Department of Biology of Physical Activity at the University of Jyväskylä in Finland (Taipale. 2013).

60 minutes LISS + 45 min leg circuit or vice versa - what's best?

The intention of the researchers was to "to examine the acute exercise induced serum hormone and neuromuscular responses and the time course of changes during recovery in response to a combined strength and endurance training session in recreationally endurance trained male and female runners and whether this response would differ if the participants started their workout with a ...

• steady state running exercise at an intensity between each subject’s previously determined individual lactate threshold (LT) and respiratory compensation threshold (RCT) for 60 minutes, or 

• a circuit leg workout with 2 minutes rest between sets that implemented both maximal and explosive strength exercises at loads of 70–85% of the individual 1RM for three sets of 5–8 repetitions, with the final repetition of each set being performed to "near failure" and explosive strength exercises of 8-10reps at a maximal velocity using only 30-40& of the 1EM load on the bilateral leg press (3 sets maximal and 3 sets explosive), the squat (3 sets maximal), loaded squat jumps (3 sets explosive), and calf raises (2 sets maximal).

In short, the question the researchers had in mind when they came up with the research design was: "What's the best way to combine 60min of steady state cardio and an intense 45min leg routine into a single workout"?

Figure 1: Change in maximal voluntary contraction (MVC) in men (left) and women (right) during, immediately after and in the recovery period after the endurance first (ES) and strength first (SE) workouts (Taipale. 2013)

As the data in figure 1 goes to show you, the results were not exactly flattering to the strong sex (=us men), whose absolute maximal bilateral isometric (MVC) strength in the endurance first (ES) trial decreased significantly (28%, p = 0.002) following the 60 minutes of jogging (E), while it remained stable in the 10 female study participants. Luckily, there was still a follow up after which we were back on par (-22% in men and -21% in women).

"The relative loading-induced decreases (D%) in strength between ES and SE differed significantly at mid in men (p<0.001). The relative decreases (D%) in strength in men and women were similar at MID; however, at post, a significant difference between ES men and ES women was observed. The absolute rate of force development (RFD) decreased during both loadings in ES and SE men (at post -19%, p< 0.001 and -22%, p = 0.003, respectively)." (Taipale. 2013)

So once again, the "fairer sex" had an "unfair" advantage, as the rate of force development of the women did not decrease significantly after either the ES or the SE trial. However, it was on ony after the "endurance first" (ES) trial that this effect reached statistical significance.

Level playing field? You must be kiddin' the girls are on dope... ah estrogen ;-)

A similar advantage was observed for the recovery of the initially equally decreased maximum voluntary contraction (MVC) in men and women. Contrary to the ladies who bounced back to normal within the first 24 hours, the MVC of the men remained significantly below the baseline levels in both the strength- (ES) and endurance first (ES) arms of the study 24 h after the endurance first trial (-14% and -15%, respectively) and was still below baseline 48 h post (p < 0.01  -11%).

Figure 2: Endocrine response to endurance (ES) or strength first (SE) workouts in men an women (Taipale. 2013)

If we set these performance outcomes in relation to the endocrine changes the scientists observed, it's quite intriguing to see the that the highly significant increase in post-workout cortisol levels right after the strength-first trial in the men coincides with faster recovery in response to doing strength before cardio workout... or should I rather say in response to doing a steady state cardio session after your strength workout the guys recovered faster?

"Men better start with strength training. Women do whatever they like?! "

The faster recovery after the strength first, endurance second (SE) trial, as well as the 343x higher GH levels after the in this arm of the study appear to speak in favor of doing your strength training first, before you hop onto a recumbent bike or treadmill and add in another 40-60min of light intensity steady state training (LISS), if you are a man! In the fortunate case that you are a member of the estrogen driven fairer sex (= a woman ;-), the study at  hand appears to suggest that it would not really make much of a difference, whether you hit the weights first or second.

For people whose main goal it is to shed fat, the reduction in leptin with cardio first may argue in favor of during your cardio first (read more).

The SuppVersity veterans out there may now feel reminded of a 2012 study by di Blasio et al. that was likewise covered in the SuppVersity news. Di Blasio et al. were the first to investigate the effects of "doing cardio in between", i.e. hopping on the treadmill or cardio equipment of your choice after the completion of a strength circuit or any other given time point in your strength workout and returning to the weights, afterwards (learn more). Unfortunately, this still isn't the answer to everthing. In fact, you don't have to browse the SuppVersity archives for posts on exercise order for very long until you hit onto an article that carries the title "Cardio First if You Want to Leave the Gym More 'Anabolic' Than You Were When You Came in?" (read more) and points you into yet another direction...

So, which of the myriad of studies do we trust?

If it were not for one major glitch in the study at hand, I  would probably end this article on the note that the singularly long follow up period in the study at hand would clearly suggest that the results Taipale et al. generated in the course of their experiment had more practical value (we all know about the fallacy of the narrow minded focus on the immediate post-workout endocrine response; don't we?) the fact that they did not control for the workload is a real bummer.

Imagine the guys simply lifted way more weight in the strength first, endurance second trial - wouldn't an increased GH response to an identical endurance workout with way more depleted glycogen stores actually be what you would have to expect? Also, we all know that when you put men and women together in the gym, the former train until they drop, while the latter do as they are told and take their time looking at the sweaty guys while fumbling around with the weights... ok, that's a cliché, but there is way more than just the splinter of truth that's at the bottom of every of these commonly held prejudices.

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Doing (intense) cardio first could promote anabolism (learn why).

Bottom line: In the end, I can only give you this advice. Try both! Try doing cardio before and after your workouts for 2 weeks each and decide afterwards which exercise order you like best. Things you should base your decision on are (a) the amount of weight you lift, (b) your performance during the cardio part of your workout, (c) how smooth the transition between one and the other goes, (d) how you feel the day after and during your next workout.

And don't forget, a glycogen depleting cardio session before your strength workout could increase the expression of the muscle building isoform PGC-1a (learn more)

References

• Di Blasio A, Gemello E, Di Iorio A, Di Giacinto G, Celso T, Di Renzo D, Sablone A., Ripari P. Order effects of concurrent endurance and resistance training on post-exercise response of non-trained women. Journal of Sports Science and Medicine. 2012 Aug; 11:393-39.
• Taipale R, Häkkinen K. Acute hormonal and force responses to combined strength and endurance loadings in men and women: the "order effect". PLoS One. 2013;8(2):e55051.

45x More Testosterone Yet Identical Increase in Protein Synthesis: MPS Response to Exercise + 25g Whey in Men vs. Women Challenges Common Wisdom About Androgens

Image 1: Is it not testosterone that makes the difference?

It is an open secret that women are having a much harder time building muscle than men, and it is another instance of (bro-)scientific wisdom that the obvious lack of testosterone in female strength athletes would be the underlying reason. Right from Stuart M. Phillips lab at the Department of Kinesiology of the McMaster University in Hamilton, Ontario, Canada, comes a new study (West. 2012) which puts yet another questionmark behind the anabolic prowess of testosterone (if you still believe that a transient increase in testosterone will help you build muscle, I suggest you read up on "The Big T" in the Intermittent Thoughts on Building Muscle).

Women are different, but it's not about protein synthesis

In the recently conducted trial Daniel W.D. West, who has also been the lead author of the "Never Sip Your Whey" study, I covered back in November 2011, undertook another attempt to identify the intricate endo- and paracrine mechanisms of skeletal muscle hypertrophy and its sex-specific variability. To this ends, West et al. recruited 5 male and 5 female subjects, who "who were habitually engaging in two to five sessions of physical activity per week including", yet did not train legs more than twice a week.

Image 1: In this case, testosterone took a backseat, as well. With synthol, protein synthesis is yet unnecessary anyway.

Note: The selection of advanced trainees as study participants is the first huge plus of this study. After all, we all know that the exercise induced hypertrophy response diminishes with training and those of you who read the whole Intermittent Thoughts on Building Muscle series will also be aware that the protein synthetic response is limited by the maximal domain size. Further growth thusly requires restructuring / the recruitment of satellite cells and installment of new myonuclei (cf. "Growing Beyond Temporary Physiological Limits"), a time-consuming and complex process which is probably one of the underlying reason for the "growth difference" between beginners and advanced strength athletes.

On the day of the experiment, the study participants, who had consumed a standardized diet containing 15% fat, 30% protein and 55% carbohydrates (the macronutrient ratio was adapted to their habitual diets) on the previous day, reported to the lab at 6am. After the infusion of the tracer that is necessary to evaluate the protein flux and an initial biopsy, all subjects performed a bout of  intense, high-volume lower body exercise consisting of

• 5 sets of 10 repetitions of leg press at ~90% of their individual 10RM, and
• 3 super-sets of 12 repetitions of leg extension/leg curl at ~90% of 12 RM

The rest intervals between the sets were 60s, so that the whole workout should not have lasted longer than max. 20min. Directly thereafter, the subjects consumed the "obligatory" (for Phillips lab this has in fact become obligatory ;-) 25g of whey protein from the usual New Zelandian source, Phillips et al. used in all their previous study (as ridiculous as this may sound but this is a nice means of standardization ;-) and rested in a supine position for the rest of the trial. Biopsies were taken and the subjects who were sent home with a launch packet consisting of their standardized meals had to report back to the lab on the following morning for another three biopsies 24h, 26h and 28h after the test workout (the subjects remained fasted and received another 25g of whey 26h post, i.e. before the last four blood samples were drawn and the last biopsy at 28h post was performed).

Figure 1: Serum testosterone levels (in nM) and myofibrillar fractional protein synthesis rate (in %/h) before and after the resistance workout, as well as on the morning and at noon of the 2nd day (data adapted from West. 2012)

As the data in figure 1 shows, the (expected) huge difference in both basal as well as exercise induced increases in circulating androgen levels (45-fold in men vs. women) had no (not even a statistically non-significant) beneficial impact on the exercise induced increase in protein synthesis in the 28h window of opportunity (cf. "Opening the 'Anabolic Barn Door' with the Key of Science").

Akt Ser473 phosphorylation increased at 1h ( P < 0.001, main effect for time) and to a greater extent in men (sex × time interaction, P = 0.018). Phosphorylation of mTOR Ser2448 was increased at 1, 3 and 5 h (P < 0.001; Figure 4B); there was a main effect for sex (men > women, P = 0.003). Phosphorylation of mTOR Ser2448 was elevated similarly between sexes after next-day protein feeding, approximately 26 h after the exercise bout (sex  × time interaction,  P = 0.49; main effect for time, 28 > 26 h,  P = 0.006).  Phosphorylation of p70S6K1 Thr389 increased at 1, 3 and 5 h (all  P < 0.001; sex × tim e interaction,  P = 0.13) and there was a significant interaction with next-day feeding (28 > 26 h in women only, sex × time interaction,  P = 0.016; data not shown). Androgen receptor content was greater overall in men (P = 0.049) but there was no significant interaction ( P = 0.47).  

The greater increase in mTOR and Akt (both hitherto regarded as the "gas pedals" of the skeletal muscle protein synthetic machinery) are not only less pronounced, than one would expect if there was a direct interaction with testosterone levels, they also lack real world significance. After all, the area under the myofibrillar protein synthesis curve (a measure for the total protein synthetic response to exercise) was identical in the 1-5h period right after the exercise and - although West et al. did not include the respective data in their article - I would suspect that the data from the subsequent day (cf. figure 1, right) would even suggest that it must have been slightly greater in the female participants.

Testosterone useless and mTOR and Akt unreliable indicators at best?

Now, which conclusions shall be drawn from these results? Is testosterone useless? Does it not contribute to the overall greater muscle mass in men compared to women? It stands to reason that this conclusion would be about as flawed as the notion that testosterone alone would suffice to build muscle. Rather than its "inefficiency" in building muscle, this study only shows that its importance in relation to the exercise-induced increase in protein synthesis is probably way overrated.

A similar point could be made for mTOR and Akt, as well, though. Or as West et al. put it in their discussion of the results and the respective implications for future studies:

In light of this disconnect, it is worth recognizing that the phosphorylation of signalling proteins is a temporal snapshot of the propagated signal for translation initiation. It is also unclear if there is a minimum threshold signal required to initiate and completely activate or  ‘turn on’ translation. If  there is such a threshold then it seems plausible that greater phosphorylation above such a  threshold would be unlikely to further amplify the signal/lead to increased rates of translation.

For a physicist or anybody who knows a thing about "energy levels" the existence of "threshold" levels in processes taking place at a molecular level should not come as a surprise.

I suspect, we are still missing the boat with our focus on protein synthesis alone

Another question, I have been hinting at in many of my previous blogposts on the insightful studies from Stuart Phillips lab at the McMaster University, is yet whether or not the acute increase in protein synthesis (alone) is actually an acceptable predictor of skeletal muscle hypertrophy, a process which, as I have explained in detail in the Intermittent Thoughts on Building Muscle is only partly mediated by the simple accrual of amino acid chains (=proteins) within existing myofibrillar domains.

Figure 2: Graphical illustration of the processes and their respective triggers which contribute to the exercise induced increase in skeletal muscle mass (click here for detailed elaborations).

If you take another look at the complex network of endo- and paracrine signalling cascades and the number of factors which contribute to a process that is generally reffered to as "skeletal muscle hypertrophy" (cf. figure 2) and is, at least in my mind, falsely reduced to the influx of amino acids into the muscle, it should be clear that testosterone does play a central role in the actual exercise induced growth response. That the latter is less pronounced than bro-science would have it (esp. when we are talking about physiological levels, cf. "Quantifying the Big T") and that testosterone itself and its metabolites, DHT and estrogen are probably of greater importance in the "restructuring" process, which in turn facilitate the accrual of even more protein within the muscle, does after all not imply that the huge differences in androgen levels are not the reason for the differential hypertrophy response in men and women - and I guess, I don't have to tell you that you just have to take a glimpse at the female IFBB (International Federation of Bodybuilding and Fitness) competitors to know that androgens can make a difference ;-)