Buffered Alternate Day Fasting + Light Aerobics Cut Body Fat, Maintain Lean Mass & Improve LDL Particle Size. Plus: Conventional Alternate Day Fasting Detrimental for Fertility

This is how the "buffered" alternate day fast works: You eat 1/4 of the White Choc Banana Cream Pie on your fasting day and a whole pie on the next one - well, not really, but the ratios would be right ;-)
I guess at least the SuppVersity facebook friends are probably going to remember the study today's article is dealing with: "Alternate day fasting and endurance exercise combine to reduce body weight and favorably alter plasma lipids in obese humans." To me that sounded like Intermittent Fasting Done Wrong Does Still Produce Great Results, When You Combine It With an Aerobic Exercise Regimen", when I first read the abstract. After taking a brief look at the full-text (thx John!),  however, my perspective on the study changed from "even a dog has its day" to "that oes look interesting, let's see whether this kind of buffered alternate day fasting" is able to take bear up with a classic intermittent fast. 

A brief warning with respect to the data in figure 1: I know that a couple of you are too lazy to actually read the article and do headline + figure hopping. If you intend to to that, please keep in mind that the data in figure 1 is from another recent study, I used to illustrate the negative effects of "real" alternate day fasting.

Not all alternate day fasting is created equal

For the course of this 12-week, randomized, controlled, parallel-arm feeding trial the participants, 61 women and only 3 men aged 25 to 65 years, overweight / obese (BMI 30-39.9kg/m²) and weight stable for at least 3 months were randomized to one of the four study arms (unfortunately the data does not allow for any conclusions, whether the men and women reacted differently to the intervention or "real" alternate day fasting the data from the rodent study I discuss in the interlude surrounding figure 1 shows that this is the case, though):
  • control group (C): sedentary, no diet
  • exercise group (E): 25, 30, 35, 40min at intensities of 60, 65, 70, 56% of the calculated HRmax (intensity and duration were increased in week 4, 7 and 10)
  • alternate day fasting group (ADF): after 4-week controlled feeding period the study concluded with an 8-week self-selected feeding period.
    As long as study subjects just have to eat what scientists serve them, every diet works. When they are however told to eat a high protein diet, for example, even the reported nutrient intake diverges massively from what the scientists had in mind, when they devised the protocol - you don't believe me? Well, then read for yourself, "What Really Happens, When Science Meets the Real World"
    "During the controlled feeding period (week 1-4) participants consumed 25% of their baseline energy needs on the "fast day” (24 h) and consumed food ad libitum on each "feed day” (24 h). [...] The diet consisted of a 3-day rotating menu plan, and all fast day meals were prepared in the metabolic kitchen of the Human Nutrition Research Unit (HNRU). Fast day meals were consumed between 12.00 pm and 2.00 pm to ensure that each subject was undergoing the same duration of fasting.[...] During the self-selected feeding period (week 8-12) subjects continued with the ADF regimen but no the fast day food was provided to them. Instead, each subject met with a dietician at the beginning of each week to learn how to maintain the ADF regimen on his or her own at home." (Bhuatin. 2013)
    During the counseling sessions the participants were also instructed to make (I quote) "healthy foodchoices on the ad libitum feed days by choosing low fat meat and dairy options and
    increasing fruit and vegetable intake." (Bhutani. 2013)
  • combination group (ADF + E): combination of alternate day fasting and exercise protocol

Table 1: Nutrient composition of the fast day diet provided to the combination and ADF groups (Bhutani. 2013)
So, as you've learned from the above overview this was no "alternate day fast", as I had expected it to be, when I read the term "Alternate Day Fasting (ADF)" in the abstract of the study. With 450kcal/day and a nutrient composition providing 50% of the energy in form of carbohydrates, and 25% (each) from fat and protein the "fasting days" were characterized by a low caloric intake (see table 1), but should not have triggered a similar starvation response as the classic alternate day fasting regimen in a recently published rodent study by Kamur et al. from which the data in figure 1 is derived.

Let's briefly take a look why "real" alternate day fasting may not be a good idea

As you can see the effect of the alternate day fasting regimen in the Kumar study, in the course of which the rodents simply did not receive any food for a whole day, had profound negative effects on the hypothalamo-gypophysial-gonadal axis - especially in the female rodents.
Figure 1: Effects of every-other day fasting vs.ad libitum feeding on ovarian weight, estradiol, lutenizing hormone, leptin, and testosterone in female and male rodents (Kumar. 2013)
Now the first thing that will jump your eye is certainly the profound increase in serum estrogen in the IF group. Looks strange and certainly not anywhere near what you would have expected right? If you think that this cannot be that bad, you are probably a man, is that right? I see... so what really is bad about the estrogen explosion is actually that it is "living proof" of the total disruption of the cyclic interplay between estrogen and progesterone that's at the heart of female (in-)fertility (on a side note: the male rodents simply got skinny fat on that regimen).

Now why didn't these adverse events occur in the study at hand?

Actually I am only assuming that there were not similar negative effects in the study at hand. After all, we don't have the respective hormonal and even in the rodents it took it's time (2 cycles) until the females were totally infertile. Changes like these would thus probably have gone unrecognized. I do however suspect that the major factors contributing to the overall hormonal decline in the rodent study were the extendended time-span without food and the overall caloric deficit, which is usually ~30-40% of the habitual intake in rodents on alternate day fasting regimen, as they do not compensate for the fasting day on the subsequent day.
Figure 2: Changes in body composition in the combined, ADF, exercise and control groups (Bhutani. 2013)
With the extended fast being absent and a ~75% reduction in calorie intake on the fasting days, only (humans are unfortunately much better in "compensating" for a lack of food on a fasting day, anyway ;-) and the huge amount of adipose tissue the rodents in the Kumar study obviously did not have as an "emergency reserve", it is therefore unlikely that the beneficial changes in body composition Bhutani and his colleagues observed in their 64 subjects (see figure 2) were accompanied by hormonal deteriorations (although 61 of them were, as previously mentioned, female).
Figure 3: Changes in lipid profile (left) and glucose metabolism in the combined, ADF, exercise and control groups (Bhutani. 2013)
It is nevertheless interesting to see that there were no significant improvements in fasting glucose, insulin or HOMA-IR (the measure of long-term blood glucose levels; not shown in figure 3) in any of the groups. Moreover, the improvements in total LDL and HDL cholesterol were only significant in the combined group and that the total amount of the inflammatory marker CRP remained essentially the same in all four arms of the 12-week intervention study.

Image 2: Ramadan fasting can serve as a relatively well studied "model" of intermittent fasting. With the additional restriction of water intake and the common practice of rising early to have breakfast there are yet non-negligible differences. You can find more information about the strengths and limitations of this model in Part 2 and Part 3 of the IF series.
A brief reminder for everyone who missed the Intermittent Thoughts on Intermittent fasting series back in the day: If there is one thing we can take away from studies investigating the effects Ramadan fasting (a Muslim fasting ritual, where you eat only when the sun goes down) it is that eating the same amount of food at different times of the day alone is not going to make you lose weight. If you do intermittent fasting in order to lose weight you still have to achieve a caloric deficit. Plus, when you are doing it during a bulk, I personally suspect that you are more likely to gain body fat, simply because your body cannot make "good use" (=muscle glycogen and skeletal muscle protein) from all the food you will be cramming down in a small fasting window. So, if you insist on IF on a bulk, do at least increase your feeding window to 8h to be able to spread your energy intake more evenly.
Based on a comparison of the data from all three groups, we can yet also conclude that it is the alternate day fasting (or probably rather the caloric deficit) that exerts the beneficial effects on what the scientists subsume under the umbrella term "CHD risk indicators":
"the combinationof ADF plus exercise decreased LDL cholesterol (12% from baseline) while increasing HDL cholesterol (18% from baseline); a change that was not noted for any other intervention. The combination group also experienced an increase in LDL particle size, and a  reduction in the proportion of small LDL and HDL particles." (Bhutani. 2013)
Only later in the discussion of their results do they mention that those "CHD risk indicators" improved to the same extend in the ADF only group - with even more significant changes in the particle profile.

Learn why breakfast is probably not the "most", but rather the least "important meal of the day" (read more).
Bottom line: The weight and fat loss are certainly intriguing. The regimen appears to be reasonably easy to follow and the fact that the improvements in glucose metabolism were marginal could well be related to the fact that the subjects were - despite being seriously overweight (!) - not diabetic.

Keeping all that in mind I am still not convinced that a regular intermittent fasting routine (16-18h fasting window on every day; learn more about intermittent fasting here at the SuppVersity) and a combined aerobic + strength training regimen would not have yielded even superior results. The average physical culturist probably will be better of with this by now almost "classic" diet routine.

  • Bhutani S, Klempel MC, Kroeger CM, Trepanowski JF, Varady KA. Alternate day fasting and endurance exercise combine to reduce body weight and favorably alter plasma lipids in obese humans. Obesity (Silver Spring). 2013 Feb 14.
  • Kumar S, Kaur G. Intermittent Fasting Dietary Restriction Regimen Negatively Influences Reproduction in Young Rats: A Study of Hypothalamo-Hypophysial-Gonadal Axis. PLoS ONE. 2013; 8(1): e52416. 
Disclaimer:The information provided on this website is for informational purposes only. It is by no means intended as professional medical advice. Do not use any of the agents or freely available dietary supplements mentioned on this website without further consultation with your medical practitioner.