If you’ve been following fitness and diet at all, you’ve more than likely heard of the term “Intermittent Fasting” (IF). IF has been getting a fair amount of buzz as of late, and has been met with a praise by some and strong criticism by others. For those of you unfamiliar with IF, it is more or less just going an extended period of time without eating. There are a number of different methods proposed, including doing one or more 24+ hour fasts per week and eating normally the rest of the days, the one meal per day plan, or simply confining all your meals within an 8 hour period and fast during the rest of the day.
Ever since first getting involved in nutrition and fitness, I have always assumed eating 5-6 small meals per day or 3 meals and 2 snacks is the best thing to do as that’s what all the magazines and professionals were saying at the time – many still are. The whole idea of this practice from a diet and fat loss standpoint is taking advantage of the thermic effect of food (TEF) more times throughout the day. TEF is the amount of energy (calories) your body must use to process the food eaten. You may have heard this referred to as “stoking the fire”. This whole idea sounds good in theory, but has never been scientifically validated. The truth is that the TEF is directly proportionate to caloric intake. Therefore, at the end of the day, as long as total calories eaten are the same, it doesn’t matter the number of meals consumed in regards to taking advantage of the TEF.
Another reason people embrace the 5-6 meals per day recommendation is because it has been proposed to be superior for hunger control throughout the day. However, a recent study by Leidy et al. 2010 showed that three meals per day, as opposed to six, was superior for appetite control. Another side-note is that this study also showed that a diet higher in protein was superior in appetite control regardless of the number of meals consumed per day.
For those looking to gain muscle or to hold on to muscle while losing fat, the idea behind consuming more frequent meals is to prevent the body from going into catabolism (breakdown mode). The whole notion of if you go more than a few hours without consuming protein that somehow your body is going to start wasting away is simply unsupported in the research. A study by Soeters 2009 looked at the effects of consuming a standard diet versus intermittent fasting and found that lean body mass and fat mass were unaffected by either treatment. More evidence debunking the muscle breakdown myth was the further observation that proteolysis (protein breakdown) was not different between the two groups.
What about breakfast? It’s the most important meal of the day, right? That’s what we’ve always been told and have often been scolded by doctors and dieticians for skipping. Many view breakfast as important to take advantage of because insulin sensitivity is higher in the morning. Exercise also increases insulin sensitivity. This pretty much means that your pancreas is required to secrete less insulin to effectively absorb the foods we eat, especially carbohydrates. This is important, as one of the causes of the epidemic of type 2 diabetes is the loss of insulin sensitivity. So if we can get through the day secreting less insulin, that’s a good thing.
However, your insulin sensitivity isn’t specifically higher “in the morning” at breakfast time; it’s higher after the 8-10 hour fast you just had while sleeping prior to eating. This happens because liver glycogen is slowly depleted when we don’t eat, thus increasing our insulin sensitivity. So, if we extend that period a little longer, possibly in addition to adding in an exercise session, it is a good possibility that our insulin sensitivity will be even higher at the time of our first meal. Furthermore insulin sensitivity remains high as long as muscle glycogen store are not full, and doesn’t vanish if you don’t carbohydrates post workout. Therefore with these methods total insulin secretion during the day could be even lower.
Although all of the previously mentioned things are important, the thing that most greatly appealed to me about IF was its practicality. The idea that I don’t have to plan out 5+ meals per day in order to maximize health and fitness sounded refreshing. Therefore, after doing some research of the various processes as well as some additional hormonal benefits such as increased growth hormone secretion and immunity effects, I decided to give IF a try.
The style I choose to do as it best fits my lifestyle is the 16/8 method (fast for 16 hours and eat during an 8 hour window). To do this I simply skip breakfast and have my first meal around noon and my last one around 7 or so. I have now been doing this consistently most days of the week for a couple of months. This frees up a lot of time for me in the morning and allows me to have MUCH larger meals when I do eat. I’m not going to lie, the first few days of trying it were tough, but now I don’t even find myself becoming hungry until around noon, and my energy levels have been fine in the morning as well.
Whether your goals are to lose fat, gain muscle, or just save time and remain healthy, you can customize the IF process to meet them. Although IF is not for everyone, I think it is something that many could benefit from giving it a try. If nothing else, it teaches you about appetite control and knowing what real hunger actually feels like. IF is NOT a diet, rather is just a lifestyle and way of eating. With IF, I (and my wife) spend less time in meal preparation and eating, I feel hungry less often, and I get more variety and feel more full when I do eat. In addition I save my biggest meal and most of my daily carbohydrates for the evening. This makes getting to sleep a breeze and also avoids the groggy feeling a high-carbohydrate meal can give you in the middle of the day.
As a side note, this goes along with questioning another common dietary myth that there is something inherently wrong with consuming carbohydrates at night, as your body will store them as fat. A 6-month trail by Sofer et al saw greater reductions in total weight, fat mass, and weight consumption in subjects who consumed a majority of their carbs at dinner as opposed to a more evenly spread consumption throughout the day in the control group with an accompanied slightly lesser drop in leptin. Leptin is the hormone which makes you feel full and decreases hunger levels.
I hope you found some of the research concerning fasting with a little bit about my experience interesting. If nothing else, hopefully it caused you to question some of the current dietary recommendations and form your own conclusions.
For more comprehensive information of IF check out these links:
If you have any further questions or comments feel free to leave them below.
Leidy HJ, et al. The influence of higher protein intake and greater eating frequency on appetitie control in overweight and obese men. Obesity (Silver Spring). 2010 Sep:18(9): 1725-32.
Soeters MR, Am J Clin Nutr. 2009 Nov;90(5):1244-51.
Sofer S, et al. Greater weight loss and hormonal changes after 6 months diet with carbohydates eaten mostly at dinner. Obesity (Sliver Spring). 2011 Oct:19(10):2006-14.
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