Friday, March 26, 2010

Alan Aragon On Intermittent Fasting

"My thoughts in IF, briefly, are that it's a highly understudied area.

The more research I review, the more I've come to find out how well-adapted the human species is to prolonged periods of zero food. There are several variants of IF, some are less conducive to typical recomp goals than others. I have come to appreciate many of the virtues of the incarnation of IF that Martin Berkhan has developed. In the past I have been highly critical of lower meal frequency, but much of that was a product of being stuck in the dogma of the mainstream curriculum. None of the 'stoking of the metabolic fire' stuff has been solidly supported by research. Now, whether IF has any *special* effects remains anecdotal. I will concede that I was incorrect about my former negatively slanted stance towards IF. "

- Alan Aragon

Recent quote from the forums. He is right on point with regards to intermittent fasting being a highly understudied area, particularly in the context of controlled human studies. Much of the research I'm looking at involves various confounders such as ad libitum calorie intake and no non-IF-control group. Not to mention that studies on intermittent fasting and weight training are completely lacking.

There have been some studies on athletes during Ramadan fasting, which show interesting results. I briefly mentioned one such study in this post. However, one very obvious confounder that plagues the Ramadan-studies is that of fluid restriction. One would presume this would impact various performance related parameters negatively. Yet interestingly, tests suggests that both aerobic and anaerobic performance is left fairly intact in most studies on the topic.


Tan Yew Wei said...

All the more the power of anecdote. Champion the ostensible protocols and figure out the reason why they work later, haha.

Nathaniel said...

That's great that he has finally seen the light, and been able to admit that he was wrong to dismiss IF out of hand.

IF runs contrary to the conventional wisdom of the fitness community. It's good that the mainstream is starting to catch on. Lyle McDonald, too, in recent times admits that IF might have some merit and often refers people to this site for more info.

Anonymous said...

Wow that's awesome news. I remember he wrote an article on IF a while ago. It was supposed to be objective but it didn't look very objective to me tbh. Funny thing is he wrote it with Ryan Zielonka who now seems very supportive of IF judging from some of his articles.

Anonymous said...


One caveat about Ramadan based on my own experience with friends is that while they fast during the day they eat massive quantities of food in the morning and at night which IMO negates many of the effects of fasting.

Joe said...

From what I understand the fasting length is the kicker, with increasing hormonal response and positive health markers showing up markedly at certain points, and further increasing the longer the fast. The 16 hour mark being one of those points. But I think Ramadan is a a sunup to sundown fast, which is 12 hours(?) not sure of the time of year and of course you have where on the globe you are to account for(lol@north pole muslims, please don't bomb me). So I don't think they are gaining much of the purported health benefits and fat loss properties of a longer fast anyway. And now to Martin with the highly researched and verbatim truth.

Martin Berkhan said...

The Ramadan fast is officially set between 6 am to 6 pm, but I think most muslims end the feast a few hours before bed time. You don't go to bed at 6 am on the dot after gorging yourself for 12 hrs straight. In practical terms, one would assume the fasting period to be approximately 13-16 hrs.


'One caveat about Ramadan based on my own experience with friends is that while they fast during the day they eat massive quantities of food in the morning and at night which IMO negates many of the effects of fasting.'

That might be so, but health parameters (i.e blood lipids, inflammatory markers) still show a positive trend in most studies. Body weight tends to stay stable. If anything, people seem to lose weight. I've found more studies showing weight loss rather than weight gain during Ramadan.

Nathaniel said...

Anecdotally, I have a Muslim friend. He has gained some weight recently and he was asking me what I've done to get so lean; I told him that I fast, kind of like Ramadan.

He immediately understood. He says that he loses weight every year during Ramadan, even though I know he stuffs himself at night.

I told him that if he wants to lose weight, just pretend its Ramadan again.

Mike said...

Robb Wolf, Alan Aragon, and Lyle McDonald have all mentioned your work, Martin---that obviously speaks volumes.

Keep up the great work.

Anonymous said...

I read the Zauner study supporting the fact that RMR elevates slightly during a 24-hour fast, but he explained that it likely was due to catecholamine-induced gluconeogenesis (and around the 24-hour mark during a fast, hepatic stores of glycogen are near-depleted, if I read the study correctly).

I understand that the most popular IF protocol right now entails a comparatively shorter 16-hour fast, but I can't rule out the possibility that some undesirable amino acid conversion to glucose is happening.

Not to discount the other host of benefits that the fast grants (most especially its profound effects on adherence, at least with me), but perhaps the heightened RMR isn't necessarily desirable. And even if some slight gluconeogenesis is happening, I don't mean to blow the issue out of proportion. It can't be anything that sufficient protein/fructose intake can't take care of during the feeding phase (I don't believe that GNG would hurt protein accretion in the muscles that much).

Looking forward to hearing back, M.

Anonymous said...

Martin, you should really consider finishing that book of yours...cant wait to read it.

Martin Berkhan said...


In Zauner's study urea-nitrogen appearance rate (a marker for muscle proteolysis) only became significantly different from baseline after 60 hrs of fasting. Proteolysis becomes a major issue after full depletion of liver glycogen, which is after 24 hrs of fasting at the very least (28 hrs in a sedentary man after a 100 g glucose load).

Also you say

'I read the Zauner study supporting the fact that RMR elevates slightly during a 24-hour fast, but he explained that it likely was due to catecholamine-induced gluconeogenesis '

But he also says

"An increase in the expression of uncoupling protein 3, which is highly expressed in skeletal muscle, and a direct thermogenic effect of norepinephrine may explain the increased resting energy expenditure"

And it is likely due to a combination of factors, not solely de novo gluconeogenesis.

Anonymous said...

I agree. Never sought out to discover or research IF. Found it by accident. We work with severe cases of hyperinsulinemic patients - all with A1C > 9%. Severe metabolic syndrome. Provided pancreas still produces insulin, we start low carb. Very low carb. Only vegetables in the beginning, with no restrictions on meat, fat or veggies. We've found that on non-workout days, probably half are not hungry for breakfast or lunch. Essentially following a 3 or 4 day per week 24 hour fast. They do extremely well. They lose weight, restore insulin sensitivity, reduce triglycerides, etc... It works with these guys, so we don't really care what the research says. But I'd bet that an RCT of IF on hyperinsulinemic people would show the same.

Seve' said...

I'm a Newbie to IF'er(3 weeks)and have been training HIT protocal for 3 months now. HIT and IF is very easy to do, especially Martin's 16 hour plan. Although, I fast for 24 hours once a week(never really that hungry and focused thru-out the day), and do IF of 16 hours all week, it still amazes me that I don't get hungry until that 16~18th hour. Only thing I have been fighting is current health/fitness industry's starvation theory(which if I don't eat regularly, I am loosing muscles instead of fat)at my gym and local GNC. Btw, I am only able to eat two meals in that 8 hour window, is that OK Martin? Plus, drinking a glass wine consider a small meal since it does have 80~100 cal?

Martin Berkhan said...


Yes, two meals is ok. Most do three, some do two, and a few do four. I wouldn't consider a glass of wine a meal in the traditional sense, no. Why does it matter? Obviously it will count as a fast-breaker if you have it during the fast.

Steven Sashen said...

While I know you don't advocate 1 meal per day, do you have any comments on this article, describing what looks like some really undesired effects from the 1 meal/day version of IF (and, possibly, how it may relate to what you're doing):

Martin Berkhan said...

All the negative findings can likely be explained by the time of obtaining the blood samples which I assume differs from the baseline period (x hrs away from meals, x needs to be constant in both scenarios: it's a common error/confounder in many studies on meal frequency).

Kevin said...

Just curious what your thoughts are on a slight alteration of your IF plan. I only fast during the week (rarely on weekends) but was thinking of trying this: 20hr fast from Mon-Tue, 16hr from Tue-Wed, 20hr Wed-Thu, then finish with 16hr Thu-Fri. I do resistance training Mon, Wed, Fri, with Tue and Thu reserved for either biking or swimming.

I would eat roughly 2000-2250 cal Mon, Wed, Fri, and 1100-1250 on Tue & Thu?

Any thoughts on that, or do you feel the straight 16/8 split 4-5 days/week is better? Thanks for any feedback!

Martin Berkhan said...

Don't see any obvious problems there. But only way to know for sure is to try it and see.

Calorie intake Tue and Thu looks awfully low unless you're a light weight. Hope most of those 1100-1200 kcal consists of protein. If not, you'll screw yourself over big time.

Jake said...

Based on reply to Kevin, what calorie level would you typically recommend on your "low cal" days? I'm 5'9, 165 ... not necessarily looking to lose weight, just lower body fat. I thought cardio days would be the best days to maintain lower calorie intake, with lifting days higher cal?

Thanks for any feedback.

Martin Berkhan said...

I don't give out individual and specific advice on calorie intake and macrocomposition in comments. There's too many factors to consider.

Anonymous said...

Is your website faster if I make a donation? It seems to hang forever loading on the last bit. Always.
Maybe it's the blog site.

In any event, yes I read AA origional "rebuttal" of IF and was looking for his current stand. In particular to LG prototol it would need to further examine the role the 16 hour fasting plays as opposed to eating larger meals, as opposed to eating surplus on workout days, as opposed to macronutrient composition. Difficult to analyse. Bottom line is if it works, who cares?

Anonymous said...

Martin, thanks for enlightening us. Mad respect for you man. I've been on IF for about 3 months and losing around 10% body fat.

I have couple questions if you don't mind answering it.

1. Do I break the fast if I eat something fibrous food like veggies or konnyaku jelly which has less than 10 cals / serving?

2. Can I add some equal (artificial sweetener) every time I drink coffee during my fast?

3. Is it okay if I fast more than 16 hours, let say for 20 hours and then workout with only drink BCAAs for pre-workout?

Thanks for your time Martin. You're the best!
Greeting from Indonesia!

My name is Martin Berkhan and I work as a nutritional consultant, magazine writer and personal trainer.

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