A little over a year ago, I started seriously reading about Intermittent Fasting (aka IF). The Wikipedia definition of Intermittent Fasting is:
Intermittent fasting (IF) is a pattern of eating that alternates between periods of fasting (usually meaning consumption of water only) and non-fasting. A specific form of IF is alternate day fasting (ADF), which is a 48-hour routine typically composed of a 24-hour fast followed by a 24-hour non-fasting period.
Whenever I heard holistic or religious people discuss fasting, my thoughts would be something like this:
Not for me. I need to eat to 6 meals a day, consume lots of protein and lift weights. If I don’t, I’ll lose muscle and my metabolism will drop. Missing a meal throws the body into a catabolic state. Plus it would be too difficult. I need to eat.
Then I started reading about Intermittent Fasting from nutritional gurus that coached athletes, including weight lifters. Arthur De Vany, Conditioning Research, Brad Pilon and Mark’s Daily Apple were all using and or recommending IF. However, the vast majority of nutritional experts oppose Intermittent Fasting. Both groups were smarter than me and they had a big disagreement.
I had been following the never skip a meal and keep eating protein mantra for as long as I could remember. I was relatively lean, I had gained muscle, but something was wrong.
- Whenever I got injured or got sick, I was unable to down regulate my appetite and I’d gain fat. This cycle repeated itself over and over. Longer periods of injury or sickness resulted in more fat gain.
- Weight lifters, particularly body builders, tend to eat cleaner and more healthy than any other sport. They need to gain muscle and shed fat, so they watch everything they eat. As they age, they get more and more muscle, which equates to a higher metabolism. However, at certain point I noticed they all had a puffiness from fat gain. Given their clean diet and large amount of muscle, they should be much leaner. I suspected the constant eating was playing a role.
- I started reading about pre-Agriculture man. Those that survived birth and accidents, died with more muscle on their bones than modern man. They did not eat 6 small meal day. Once the food was gone in their area, they picked up and moved on. They would go through periods of having no food. Yet they were lean, muscular and cancer free. If fasting really was catabolic then pre-Agriculture man would not have had large muscle points on their skeleton.
Intermittent Fasting had caught my attention. I was interested in getting leaner or at least not gaining fat during my non-active periods. The anti-inflammatory effects and autophagy were also interesting to me. I also recognized that I had reached the limit of where 6 low-glycemic meals a day could take me. However, I still had two fears I needed to address.
#1 Is fasting catabolic?
Not for pre-Agriculture man is wasn’t, but why not? When you fast your insulin levels drop big time. Your Growth Hormone (GH) levels increase. Exercise, especially interval and weight training, also elevate GH levels. GH is protein/muscle sparing and GH helps the body mobilize fat for fuel. Not eating for long periods of time (starvation) is catabolic, short periods of fasting aren’t. In a recent post titled Protein Breakdown by Brad Pilon, he cited data showing the body targets visceral fat over muscle by a significant amount, even using a full 7 day fast (non-IF).
During a 7 day fast, your liver will lose 40% of its nitrogen (a marker of protein breakdown) and your visceral organs (your G.I. system) loses anywhere from 20-28%. Your muscle, skin and skeleton only lose around 8%
#2 Will my metabolism drop and cause fat gain?
The very act of eating protein and carbohydrates is thermogenic. You will burn off 20-30% of those calories just by eating. So, yes your metabolism will drop by not eating. However, since you can never burn off more than you can eat, each meal ends with a caloric surplus.
In the end, I decided that I needed to know if Intermittent Fasting would work for me. Both sides of the IF debate knew more science and nutrition than me. Only my own tests would answer the question. If I lost muscle or strength, I could end the experiment and resume the old way. Plus, I would only try the IF one day a week.
It has been about 5 months since I started this experiment. What happened? I’ll save that for my next post.
Mar 14, 2014 — 12:31 pm
Buddy, this is great stuff. I started on your /best-of/intermittent-fasting/ page and am working my way through.
I’ve been weight-training for countless years and IF has always come up. Never given it a go with full commitment, but after reviewing your articles I’m going to give it my full attention.
I’m already a light eater. I watch my daily macros and such, but eating the ~6-8 meals a day that most everybody swears by just isn’t something I have ever been comfortable doing. I’m just too busy.
Great article/section on IF!
Mar 15, 2014 — 7:25 am
@Marcus – Glad you are finding the posts helpful.