Fasted AM Cardio - No Measurable Physiological Benefits in Terms of Fat Loss & Body Composition, Meta-Analysis Says

Rope skipping is an excellent choice for HIIT cardio training... albeit, just like for so many others, the effects of doing it fasted have never been investigated.

It has been debated for decades and still, the Australian researchers Daniel Hackett and Amanda D. Hagstrom are the first to attempt to answer the question "whether training in fasted compared to fed states leads to greater weight loss and whether this practice results in beneficial or detrimental changes in body composition" (Hackett 2017) by the means of a systematic review and meta-analysis.

How's that? Well, if I tell you that Hacket & Hagstrom found only five RCTs to be included in their analysis there's probably no longer a need to answer this question.

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The scientists included all studies that were (1) randomized and non-randomized comparative studies; (2) published in English; (3) included healthy adults; (4) compared exercise following an overnight fast to exercise in a fed state; (5) used a standardized pre-exercise meal for the fed condition; and (6) measured body mass and/or body composition. Risk of bias in individual studies was assessed using the Cochrane risk of bias tool.

There were a total of 96 participants (60 males and 36 females) aged 21–27 years (Table 1). Three studies included only male participants  while the other two studies had only female participants [19,20]. The majority of participants had an exercise background such as track and field  or regularly played sports . Participants for one study were described as being previously sedentary. The exercise interventions involved 3–4 supervised sessions performed over 4–6 weeks. High intensity interval training (cycling) was performed in one study, continuous cycling in three studies, and continuous treadmill exercise in one study" (Hackett 2017).

 All five studies assessed changes in body mass, but only two of them assessed changes in body fat (one study via BodPod, the other via DXA) - one study assessed changes in lean body mass, and one study assessed changes in fat-free mass.  For the meta-analysis, data from lean body mass
and fat-free mass was combined as it has previously been shown not to impact results (Stonehouse 2016).

The inter-group effect sizes  for the interventions on body mass for the combined, male, and female analyses were trivial (ES = 0.02 to 0.05) with no significant difference between interventions

That's bad news for fasted cardio advocates, but it's also bad news that the most important analyses, i.e. that of changes in % body fat and lean mass could only be performed on females because the studies that included males only did not include these outcome measures.

Table 1: The effects of fasted versus fed exercise on weight loss and composition (Hacket 2017).

The results of the analysis of the pooled data were quite disappointing, anyway - here's a summary:

• The intra-group ES for fasted and fed exercise on % body fat for females were small (ES = −0.10 to −0.12) and were not significant (Table 1). 
• The inter-group ES of the interventions on % body fat were trivial (ES = 0.05) and not significant. 
• The intra-group ES of the intervention on lean mass for females were trivial (ES = 0.01) and were not significant (Table 1). 
• The inter-group ES of the interventions on lean mass was also trivial (ES = 0.04) and not significant. 

And no, in the absence of heterogeneity between studies (I2 = 0%), there's little doubt that - if there's an effect (and I don't doubt that you may have benefitted repeatedly), it is probably of behavioral origin (e.g. if you do fasted AM cardio, you actually do it and don't skip your planned PM sessions; if you do fasted AM cardio you usually have breakfast afterwards - especially, if you'd do that anyway doing it this way around may protect you from post-cardio hunger pangs; etc.).

Schoenfeld's 2014 study is one of the five papers that made it into the meta-analysis. He shows quite conclusively that there's no fat loss magic in doing cardio fasted if the 24h energy deficit is standardized | read more

So what do you have to know? While "fasted cardio" may work as a charm on psychological/behavioral grounds, there's no evidence to believe that there are systemic physiological benefits to training after an overnight fast.

In that, it is worth considering that the data in pertinent studies show minimal changes in body mass and composition following aerobic exercise interventions in both fasted and fed states, anyway.

The notion that you can use a lot of cardio to get jacked is thus - at least in the absence of appropriate caloric restrictions - futile undertaking and that has to be said about both doing it in the fasted and fed state.

That's also why the authors of the meta-analysis at hand are right, when they conclude that their "findings support the notion that weight loss and fat loss from exercise is more likely to be enhanced through creating a meaningful caloric deficit over a period of time, rather than exercising in fasted or fed states" (Hackett 2017). Hackett & Hagstrom are yet also right that "due to the limited number of studies and hence insufficient data" we got to be careful w/ our interpretation of the data.

Moreover, if fasted cardio has worked to your advantage in the past - be that for psychological and/or behavioral reasons - even a meta-analysis won't change that. After all, doing cardio on empty can be one building block of your strategy to achieve the "meaningful caloric deficit" of which Hackett & Hagstrom rightly point out that it is the cornerstone to any fat loss regimen | Comment!

References:

• Hackett, Daniel, and Amanda Hagstrom. "Effect of Overnight Fasted Exercise on Weight Loss and Body Composition: A Systematic Review and Meta-Analysis." Journal of Functional Morphology and Kinesiology 2.4 (2017): 43.
• Stonehouse, Welma, et al. "Dairy Intake Enhances Body Weight and Composition Changes during Energy Restriction in 18–50-Year-Old Adults—A Meta-Analysis of Randomized Controlled Trials." Nutrients 8.7 (2016): 394.

8 Wks W/ Weekly Fasting Day Trigger 6% Reduction of Body Fat % + Improved Mood on Follow Up | Plus: The Three Main Mechanisms Behind Intermittent Fasting's Health Benefits

On fasting days <300ml of vegetable broth, juices or teas were OK.

Since the title of the study already gives it away, I suggest that we address the phrase "non-randomized", which describes an essential characteristic of a recent 8-week study that was conducted by scientists from the Freie Universität Berlin (Germany), right away. Yes, the study was designed as a non-randomized controlled clinical trial with two arms, involving healthy volunteers only. And yes, it is indeed very likely that the subjects who chose to be in the fasting group had a positive bias towards 'not eating' once a week...

...but hey, let's be honest: Isn't that the "real world"? I mean people who will subscribe to any form of intermittent fasting protocol usually do so voluntarily. The fact that the study was nonrandomized is thus in line with the authors' intention which was to "evaluate whether intermittent fasting is an effective preventive measure and whether it is feasible for healthy volunteers under everyday-conditions." (my emphasis in a quote from Kessler 2017).

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The study itself consisted of an 8-week intervention period, followed by a four-month follow-up (the total study duration was thus 6 months). Outcomes were assessed at baseline, after eight weeks, and after six months. As previously hinted at, fasting was not obligatory, volunteers who were not interested in fasting served as a control group.

The intervention itself is easy to describe: Participants in the fasting group were asked to continue their regular nutritional habits on the non-fasting days, while the control group maintained their habitual nutrition throughout the whole period. More specifically, ...

• fasting was done on a self-chosen weekday (e.g. Monday) 
• patient adherence was defined by conducting at least six of the eight eight overall days of fasting during the eight week intervention period
• fasting days were defined as days during which the subjects abstained from solid food for at least the period between 00:00 and 23:59, and accumulated a maximum total energy intake of 300 kcal/d resulting from defined fasting beverages
• allowable "fasting beverages" were standard fruit and/or vegetable juices 2 x 200 ml/d, clear vegetable broth (maximum 300 ml/d), ≥ 750 ml/d hot, unsweetened herbal teas, ≥ 1500 ml/d of non-sparkling, resp. tap water at room temperature
• for better compliance cardamom, vanilla, and cinnamon were allowed in small quantities in order to enhance the taste of grain based liquids
• unsweetened black tea, green tea, and black coffee were also allowed in small quantities (maximum 2 servings)

Study outcomes included changes of metabolic parameters (insulin, glucose, insulin-resistance, IGF-1, BDNF, lipids, liver enzymes, HbA1c) and coagulation-markers; bioelectrical impedance analysis; body mass index; abdominal girth; blood pressure; general quality of life (WHO-5 questionnaire), as well as mood and anxiety (HADS, POMS, Flourishing-Scale, VAS, Likert-scales). The intervention consisted of a fasting day which was repeated every week for eight weeks, with abstinence from solid food between 00:00 and 23:59 at a minimum and a maximum caloric intake of 300 kcal on each fasting day. A per protocol analysis was performed, p-values <0.05 were considered as significant.

A sample fasting day: 200ml fruit or vegetable juice in the morning, 300ml vegetable stock for lunch, 200ml vegetable or fruit juice in the evening plus 2250 ml of tea and water distributed over the whole day. Laxative measures before, during and after the fasting days were not part of the protocol (e.g. standard Polyethylenglycol solution, Glauber or Epsom salt).

The analysis of the subjects' (N=22 in the fasting, N=14 in the control group) baseline data showed no significant between-group differences. Overall, the scientists observed that the "[b]aseline values for participants of both groups reflect a very healthy, middle-aged and predominantly female population" (Kesseler 2017) - a group with a high variance in BMI (despite normal baseline BMI, hip measurement and abdominal girth values) and a similar distribution pattern for IGF-1 baseline values.

Adherence to fasting was OK - accordingly, it doesn't mess with the results

Of the twenty subjects in the intervention group, nine subjects completed six fasting cycles, four subjects completed seven fasting cycles, and seven subjects completed eight fasting cycles.

What do we know about intermittent fasting (Patterson 2017): Mostly based on rodent studies, we know that intermittent fasting and restricting the availability of food to the normal nighttime feeding cycle improve metabolic profiles and reduce the risks of obesity and obesity-related conditions, such as nonalcoholic fatty liver disease, and chronic diseases, such as diabetes and cancer. For humans, this is not satisfactorily studied, though. What appears to be relatively certain is that intermittent fasting regimens are not harmful physically or mentally (i.e., in terms of mood) in healthy, normal weight, overweight, or obese adults.

The mechanism that's behind the beneficial effects of fasting is complex and involves (a) changes in the gut microbiome, (b) direct and indirect effects of the circadian clocks, and (c) lifestyle changes related to diet (e.g. no late-night chips binges, involuntary reduction in total energy intake, etc.), activity and sleep (Patterson 2017).

Overall (humans + rodents), studies suggest that almost any intermittent fasting regimen can result in some weight loss. Among the 16 intervention trials included in Pattersons 2017 review, 11 reported statistically significant weight loss. With regard to the often-cited beneficial effects on insulin concentrations, improvements in lipids, or reductions in inflammatory factors, the contemporarily available evidence is mixed, with alternate-day fasting, in particular, resulting in both, weight loss, as well as reductions in glucose and insulin concentrations, in the three pertinent studies in Patterson et al.'s 2017 review.  According to the authors of the review, alternate day fasting may yet not be practical because it leads to intense hunger on fasting days. The hunger pangs can be avoided or ameliorated by modifying the ADF regimens (e.g. protein-modified fast on every other day).

In that, it is important to remember, though that "research has not demonstrated that alternate-day fasting regimens produce superior weight loss in comparison to a standard, continuous calorie restriction weight-loss plans" (Peterson 2017). Furthermore, potential interactions of intermittent fasting and other health behaviors, such as diet, sleep, and physical activity have not sufficiently been studies. The same goes for links between intermittent fasting regimens and clinical outcomes, such as diabetes, cardiovascular disease, cancer, or other chronic diseases, such as Alzheimer’s disease.

Figure 1: From baseline, to wk 8 there was a sign. reduction in body fat % (relative 6%, absolute -1.79% | Kressler 2017)

In view of the fact that the scientists' sensitivity analysis that included only patients with eight cycles revealed no significant differences for the evaluated outcomes, it doesn't seem as if the failure to adhere to all 8 fasting days in 50% would have ruined the data, though.

The number of adverse events, i.e. 69 vs. 17 in the fasting vs. control group confirms that fasting, especially when your body isn't accustomed to it, can have side effects.

The most common side effects that could be related to fasting were headache, migraine, nausea, ravenousness, circulatory disturbance, hunger, general feeling of weakness, tiredness, stomach ache, meteorism, heartburn and cold sensations in the body.

The beneficial effects of fasting on (a) total body fat and (b) mood and anxiety scores were small, but measurable and statistically significant... albeit probably without practical relevance. 

For me, personally, it is not surprising that an intervention that consisted of only one fasting day per week did not have statistically significant effects on the subjects' body weight, BMI, glucose management or blood pressure. In fact, I am rather surprised that Kessler et al. found significant treatment effects on total body fat and the results of the HADS mood and anxiety test.

Figure 2: Changes in HADS scores and blood pressure from baseline to wk 8 (V1) and 6-mo follow-up (V2 | Kessler 2017)

Even if you're a fasting advocate, though, you will probably have to agree with the scientists and admit that "none of the between-group differences were clinically relevant" (Kessler 2017).

The assumption that the mood changes, the authors detected after the follow-up were a result of fasting seems to be very questionable, ... to say the least.

This is particularly true in view of the fact that the pronounced improvement in HADS scores occurred after the intervention phase. At the end of the 8-week intervention, the changes in HADS total scores were identical in both groups (-0.82±2.67 for fasting, -1.93±3.34 for control, p = 0.39). The subsequent increase which was supposedly related to the previous fasting could thus have been mere coincidence - or, even worse, a result of the subjects being allowed to finally eat whenever you wanted, again ;-)

Similar caution should be exerted with respect to the - on an absolute basis - quantitatively small changes in body fat.

While the reduction in body fat occurred, when you would expect to see it, the absolute changes were small (from 28% to 26%) and despite their statistical significance, potentially an artifact of the measuring method. Especially in view of the fact that similarly relevant changes in waist circumference were not observed, it is furthermore questionable, whether that's metabolically relevant visceral and belly fat or rather relatively benign appendicular fat the subjects lost.

2-fasting days just as effective for weightloss as an isocaloric continuous energy restriction (vs. non-controlled, non-restricted study at hand).

Safe and feasible, but not really useful?! "Fast once a week and get all the benefits of calorie restriction/fasting?" While you may have previously suspected that this claim must be a scam, you do now have Kessler's latest study to prove it: there are no clinically relevant benefits of once-a-week fasting in healthy volunteers - at least not a very uncontrolled, but realistic real-world scenario (which does allow for (over-)compensation on non-fasting days) as it was used in the study at hand.

This lack of practically relevant differences in the short run is in line with a recent, more tightly controlled study, I discussed only recently. Said study compared the effects of intermittent (two days per week) and continuous caloric restriction only to find virtually identical weight and fat loss in both groups (learn more).

The overall take-home-message is thus "fasting is feasible and safe", not "fasting is an easy way to get jacked, healthy and happy"... although I bet you will see this study being misinterpreted in this way on pro-fasting media outlets very soon.

Against that background and in view of the previously outlined "?" we have to put behind the alleged improvements in mood and body fat (see last paragraphs of this article), I would not interpret the study at hand as evidence in favor of weekly one-day juice-/broth-fasting. I mean, if (intermittent) fasting - in which way or form you may use it - promotes weight/fat loss, there's a 99.9% chance it does so because it modulates your energy balance; and in most of the cases that's not due to innate effects like the previously described increase in RMR with breakfast skipping & co, but rather by simply reducing your food intake - effects on the circadian rhythm and gut hormones, on the other hand, contribute to the various health benefits of (intermittent) fasting | Comment!

References:

• Conley, Marguerite, et al. "Is two days of intermittent energy restriction per week a feasible weight loss approach in obese males? A randomised pilot study." Nutrition & Dietetics (2017).
• Kessler, Christian S., et al. "A Non-Randomized Controlled Clinical Pilot Trial on 8 Weeks of Intermittent Fasting (24h per week)." Nutrition (2017).
• Patterson, Ruth E., and Dorothy D. Sears. "Metabolic Effects of Intermittent Fasting." Annual Review of Nutrition 37.1 (2017).

7-Day Protein-Modified Fast - All the Benefits of Fasting W/Out the Risk of Muscle Loss? Human Study Says...

Lean wild salmon would be a good protein source for a PSMF regimen.

If you are not familiar with the idea of a "protein modified fast" here's what it's all about: in order to minimize the use of lean tissue as a source of energy, a protein-sparing modified fast (PSMF) will combine very low calorie diet with some (often high amounts of) protein, fluids, and vitamin and mineral supplementation.

Matthew Furber and his colleagues from the GSK Human Performance Lab and the University of Hertfordshire and the Anglia Ruskin University were recently able to proof that this special variety of fasting will not only help you shed body fat at a low risk of significant lean mass declines, it will also have profound health benefits.

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As the authors highlight, the past decade of research has demonstrated quite conclusively that a hypocaloric high fat/low carbohydrate (HF/LC) diet can up-regulate transcriptional markers of mitochondrial biogenesis; accordingly, this is what the scientists based their subjects' diets on.

Figure 1: Macronutrient comp. of the diets (for both, the EM = maintenance +ER = calorie restricted diets | Furber 2017)

Forty-five healthy male participants were randomly assigned one of four intervention diets: eucaloric high-protein (PRO-EM), hypocaloric high-protein (PRO-ER), eucaloric high-carbohydrate (CHO-EM) or hypocaloric high-carbohydrate (CHO-ER). The macronutrient ratio of the high protein diet and high carbohydrate diets was 40:30:30% and 10:60:30 % (PRO:CHO:FAT) respectively. The "[e]nergy intake for the hypocaloric diets were calculated to match resting metabolic rate" (Fuber 2017).

Ok, I know this is not a "fast", but I stick to the term, 'cause the authors use it

Participants visited the laboratory on 3 occasions each separated by 7 days. On each visit body composition, resting metabolic rate and a muscle biopsy from the vastus lateralis was collected. Prior to visit 1 and 2, the subject simply consumed their habitual diet, which thus served as a control. Between visit 2 and 3, the intervention diet was consumed continuously for 7-days.

Figure 2: The scientists observed increases in AMPK, Sirt1+3 and PGC-1a, proteins that mediate the health benefits of fasting and, compared to the high-CHO fast, a sign. reduced lean mass loss + slightly enhanced fat loss (Furber 2017).

The scientists' analysis of the data shows that, in the PRO-ER group, a significant increase in
AMPK, PGC-1α, SIRT1 and SIRT3 mRNA expression was observed - a slightly greater increase than in the other groups, that is (p < 0.05).

Furthermore, no difference in lean mass (LM) loss was observed between the PRO-ER and CHO-EM groups, despite ~30 % reduction in calorie intake - and that's just what the many N=1 reports on the results of short-term PSMF regimen say, as well.

The high protein content of the diet also kept the resting metabolic rate (RER) of the subjects elevated. The RER of the subjects dieting on a high carbohydrate diet, however, declined by 4.3% (Furber 2017).

What does that mean, practically speaking: The study at hand may confirm that a 40:30:30% (PRO/CHO/FAT) diet consumed for 7 days will shed significant amounts of body fat while having less of a negative impact on your lean mass than its high(er) carbohydrate cousin. Furthermore, the high protein way of dieting ameliorated te effect of protein on the diet-induced reduction in energy expenditure (RMR +2% in PRO-ER vs. RMR -4% in CHO-ER.

That's all great new, but it's not worth the virtual paper it was printed on. After all, even if a loss of glycogen made the results look extra bad, a ratio of lean to fat mass loss of almost 1:1 is unbearable. You can do better and I've pointed out how in previous articles like this one | Comment!

References:

• Furber M, Anton-Solanas A, Koppe E, Ashby C, Roberts M, Roberts J. "A 7-day high protein hypocaloric diet promotes cellular metabolic adaptations and attenuates lean mass loss in healthy males." Clinical Nutrition Experimental (2017), doi: 10.1016/j.yclnex.2017.05.002.

Monthly 5-Day 'Fast' Supposedly Helps Healthy Humans to Keep Aging, Cancer, Diabetes & Heart Disease in Check

Even on the five fasting days per month your plate doesn't have to be completely empty. Real foods, however, weren't served in this trial.

An international consortium of scientists has recently published an intriguing study about the effects of a "fasting-mimicking diet" on markers/risk factors for aging, diabetes, cancer, and cardiovascular disease (Wei 2017). The study builds on the ever-increasing evidence that calorie restriction or changes in dietary composition can enhance healthy aging.

Now, as effective and healthy as it may be, fasting is not exactly what the average pre-diabetic (of whom the study at hand shows that he would benefit most) wants to do and/or what he or she can adhere to in the long run.

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To test whether it may not even be necessary to fast for weeks and months, Min Wei et al. conducted a randomized clinical trial with 100 generally healthy participants. With a cross-over after 50% of the study period of three months, the study ensured that all subjects were fed the fasting-mimicking diet (FMD) group for 3 months. Aside from being low in calories and protein -

• day 1: ~4600 kJ = 1100kcal | 11% protein, 46% fat, and 43% carbohydrate 
• day 2-5: ~3000 kJ = 717kcal | 9% protein, 44% fat, and 47% carbohydrate

- the diet that was consumed for 5 consecutive days per months for three months (with a lower kcal-deficit on day 1 vs. 2-5 that's supposed to make it easier to get into the fast), each, was plant-based diet, and designed to attain fasting-like effects on the serum levels of IGF-1, IGFBP-1, glucose, and ketone bodies.

Figure 1: Overview of the study design (left) and post hoc comparisons for changes in risk factors for age-related diseases and conditions by baseline subgroups (right | Wei 2017).

To compensate for the lack of macro and micronutrients the scientists used ready-made food products from USC and L-Nutra (www.prolonfmd.com): vegetable-based soups, energy bars, energy drinks, chip snacks, tea, and a supplement providing high levels (25% of the RDA per serving for most ingredients) of minerals, vitamins, and essential fatty acids were on the subjects' daily menu.

Figure 2: Overview of changes in several markers of metabolic and overall health (Wei 2017).

As you can see in the table on the right-hand side of Figure 1 and the series of graphs in Figure 2, fasting for only 5 out 30 days of a months and a total of 15 days in 3 months yielded quite impressive effects in all (Figure 2) and even greater effects in those subjects with lower metabolic health (see Figure 1, right) - a statistical significance between the improvements in those with the worst and best risk factors in Figure 2 was yet observed only for glucose and IGF-1.

The parameters improved, but you may still not live longer or stay healthier! It's not the lack of improvements in plasma lipids an it's neither the relatively small effect size of many changes. It is the mere fact that the glucose, insulin, IGF1 and triglyceride levels of the average Westerner will still skyrocket acutely on the 25 days of the months on which they don't fast. And that's really bad news, because many of the unassessed markers like the postprandial glucose and lipid levels are highly significant predictors of heart disease (Lefebvre 1998; Hanefeld 1999; O’Keefe 2007) or cancer (Michaud 2002; Prescott 2014; Larsson 2016) - to reduce the level of fasted / non-postprandi-ally measured markers of disease risk is thus clearly not enough to predict the true reduction of disease risk.

Bottom line: Overall, it is thus prudent to say that the three FMD cycles every subject underwent triggered significant reductions in body weight, trunk, and total body fat; lowered blood pressure and decreased insulin-like growth factor 1 (IGF-1) without serious side effects.

What looks like an easy way out does yet also have it shortcomings: (a) the subjects' blood lipids did not improve (neither total, nor LDL, or HDL cholesterol and their ratios); (b) the treatment may have been free of health-relevant side-effects, side-effects that will have many people fall off the wagon, however, existed, nevertheless (e.g. fatigue, weakness or headache see additional figure); (c) with no effect on peak values of glucose, insulin, IGF-1 etc. on the non-fasting days, it's far from being obvious that the treatment will have any of the hoped for long-term effect.

Especially (c) is something you should remember: before the scientists produce the long-term evidence that confirms that 5 days every month are enough to let you live longer, reduce your cancer, CVD and diabetes risk, I still recommend to change your lifestyle on 365 days of the year - that's the tried and proven method to live long(er) and healthy(-ier) | Comment!

References:

• Hanefeld, M., et al. "Postprandial plasma glucose is an independent risk factor for increased carotid intima-media thickness in non-diabetic individuals." Atherosclerosis 144.1 (1999): 229-235.
• Larsson, Susanna C., Edward L. Giovannucci, and Alicja Wolk. "Prospective Study of Glycemic Load, Glycemic Index, and Carbohydrate Intake in Relation to Risk of Biliary Tract Cancer." The American journal of gastroenterology (2016).
• Lefebvre, P. J., and A. J. Scheen. "The postprandial state and risk of cardiovascular disease." Diabetic Medicine 15.S4 (1998).
• Michaud, Dominique S., et al. "Dietary sugar, glycemic load, and pancreatic cancer risk in a prospective study." Journal of the National Cancer Institute 94.17 (2002): 1293-1300.
• O’Keefe, James H., and David SH Bell. "Postprandial hyperglycemia/hyperlipidemia (postprandial dysmetabolism) is a cardiovascular risk factor." The American journal of cardiology 100.5 (2007): 899-904.
• Prescott, Jennifer, et al. "Dietary insulin index and insulin load in relation to endometrial cancer risk in the Nurses' Health Study." Cancer Epidemiology and Prevention Biomarkers (2014): cebp-0157.

Adaptation to Intermittent Ramadan Fasting Takes Time, but Eventually Mood, Fatigue, and the Quality of Life Improve

No, it wasn't a button like this which made the subjects happy.

It took some time, yeah, but after a few weeks the participants, students of the Hannover Medical School, where the trial was conducted actually felt better, not - as the scientists who conducted this Ramadan fasting study had expected - worse than without their religious fasting.

But let's not go too fast, here. The subjects had volunteered to participate in the study and were non-randomly assigned to a fasting (FG) and a non-fasting (NFG) group (according to their individual plans | Nugraha. 2016).

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To be eligible into the FG, participants had to: (1) be healthy, (2) be older than 18 years of age, (3) intend to fast the whole month of Ramadan, (4) have fasted during Ramadan at least once before, (5) understand the German or English language. For the NFG, all subjects had to meet the criteria of the FG, except that they would not be fasting. Furthermore (and that's IMHO a pity) The NFG participants were assessed only at T1 and T3. That's in contrast to their peers in FG, where participants were assessed at four different points: one week before Ramadan (T1), mid-Ramadan (T2), the last days of Ramadan (T3), and one week after Ramadan (T4).

Figure 1: While the perceived fatigue of the subjects skyrocketed in the early phase of the Ramadan fast, it dropped during the latter phase and achieved an all-time low in the post-Ramadan week (this peak is missing from the fatigue severity score that kept declining continuously | not shown in Figure 1). The subjects' overall mental health, on the other hand, improved, but without a significant treatment effect due to religious fasting (Nugraha. 2016).

Unfortunately, the lower "resolution" in the NFG group, makes it impossible to directly compare the mood and QoL progression over time.

Examples of effects of intermittent fasting on different organ systems.

More fasting news: 48h of fasting make young weight lifters more aggressive and jumpstart their parasympathetic activity, as well as prefrontal-cortex-related cognitive functions, such as mental flexibility and set-shifting (Solianik. 2016). In young women (mean age 25 years) fasting leads to increased irritability, bit also to positive affective experiences of increased sense of achievement, reward, pride, and control (Watkins. 2016). Furthermore, more and more studies seem to confirm that the health benefits of intermittent fasting (in its various forms) do not depend on weight loss (Aksungar. 2016) and comprise a long list that goes way beyond the things Mattson et al. summarized graphically in the figure to the right:

Limit inflammation, reduced oxidative stress and cellular damage, improved circulating glucose, reduced blood pressure, alteration in IGF-1 levels, improve metabolic efficiency and body composition, including significant reduction in body fat and weight in obese individuals, reduced LDL and total cholesterol levels, prevention or reversal of type 2 diabetes, as well as slow its progression, improved immune function, and shift stem cells from a dormant state to state of self-renewal, improved pancreatic function, insulin and leptin levels and insulin/leptin sensitivity, normalized ghrelin levels, reproduction of some of the cardiovascular benefits associated with physical exercise, protection against cardiovascular disease, modulation of the levels of visceral fat, boost of mitochondrial energy efficiency and protection of striatal neurons against mitochondrial toxicity, elimination of sugar cravings as the body adapts to burning fat instead of sugar, promotion of human growth hormone production (HGH), lower triglyceride levels, elevated production of brain-derived neurotropic factor (BDNF), stimulation of neurogenesis and triggering of brain chemicals that protect against changes associated with Alzheimer’s and Parkinson’s disease, enhanced dopamine overflow in striatum, attenuated age-related decrease in cardiac synaptic terminal norepinephrine uptake, attenuation of age-related loss of cortical dendritic spines, protection against seizure-induced hippocampal damage, memory impairment and focal ischemic brain injury, enhanced learning and motor function in models of aging, slow age-related loss of spiral ganglion neurons while aging, and the list will probably expand further in the years to come (Uher. 2016).

What the data I've plotted for your in Figure 1 still tells you is that the subject's perceived level of fatigue skyrocketed in the initial phase of Ramadan fasting and improved to sub-control levels at the end and one week after Ramadan fasting. At the same time their mental health scores improved, albeit not significantly.

Figure 2: Mood and sleepiness show a similar pattern over the course of the trial (Nugraha. 2016).

Similar trends were observed for the subjects' mood and their sleepiness scores, which were  was measured by using the Epworth Sleepiness Scale (ESS), a self-administered questionnaire with 8 questions that are rated on a 4-point scale (0–3) to yield a score ranging from 0 to 24, with higher scores indicating that person's average propensity of daytime sleepiness increased.

Table 1: Body composition before, during, and after Ramadan (Nugraha. 2016).

The effects on the subject's body composition are significantly less obvious. There were no significant differences in all parameters at both T1 and T3 when comparing FG and NFG. Plus: the way the figures "evolved" make me question the accuracy of the InBody machine (InBody 230; Model MW160, Korea) the scientists used.

Figure 3: Genotype-specific effects of modified fasting (total energy intake <350 kcal/day) on the mood of 108 subjects (Michalsen. 2010). Note: Even though the TT group saw no significant increase in mood, their mood levels did eventually improve - it just took longer than it did for subjects with the CC and CT allele.

So what do you have to remember? The study at hand proves that there is indeed something people often call an "induction phase", i.e. a phase during which your body has to get accustomed to the new meal timing. After that, however, Ramadan (=intermittent fasting from dusk till dawn) shares the same mood improving effects Michalsen, et al. (2010) and Fond et al. (2013) ascribe to prolonged fasting, which is associated with increased brain availability of serotonin, endogenous opioids, and endocannabinoids.

Whether and to which extent you will benefit, however, may depend on your individual gene set with a 2009 study by Michalsen, et al. (see Figure 3) indicating that your individual GNB3 C825T polymorphism determines whether and how fast your mood benefits from fasting | Comment!

References:

• Aksungar, Fehime Benli, et al. "Comparison of intermittent fasting versus caloric restriction in obese subjects: A two year follow-up." The journal of nutrition, health & aging (2016): 1-5.
• Fond, Guillaume, et al. "Fasting in mood disorders: neurobiology and effectiveness. A review of the literature." Psychiatry research 209.3 (2013): 253-258.
• Mattson, Mark P., Valter D. Longo, and Michelle Harvie. "Impact of Intermittent Fasting on Health and Disease Processes." Ageing Research Reviews (2016).
• Michalsen, Andreas, et al. "Hunger and mood during extended fasting are dependent on the GNB3 C825T polymorphism." Annals of Nutrition and Metabolism 54.3 (2009): 184-188.
• Michalsen, Andreas. "Prolonged fasting as a method of mood enhancement in chronic pain syndromes: a review of clinical evidence and mechanisms." Current pain and headache reports 14.2 (2010): 80-87.
• Nugraha, et al. "Effect of Ramadan fasting on fatigue, mood, sleepiness, and health-related quality of life of healthy young men in summer time in Germany: A prospective controlled study."Appetite - Available online 24 December 2016 | In Press, Accepted Manuscript 
• Solianik, Rima, et al. "Effect of 48 h Fasting on Autonomic Function, Brain Activity, Cognition, and Mood in Amateur Weight Lifters." BioMed Research International 2016 (2016).
• Uher, Ivan, et al. "Intermittent fasting and its influence on health." Physical Activity Review 4 (2016): 184-191.
• Watkins, Ellen, and Lucy Serpell. "The psychological effects of short-term fasting in healthy women." Frontiers in Nutrition 3 (2016).