It’s been a bit crazy as the Match concluded. I haven’t focused on posting with so much else going on. But….
I saw a recent study today that warranted a short post, as it is about Intermittent Feeding (aka Intermittent Fasting, IF). I am fascinated by IF because of how it can quickly change the metabolic environment in prediabetes and obese individuals. In addition, a new study points out why IF might be better then traditional daily dieting.
“Intermittent versus daily calorie restriction: which diet regimen is more effective for weight loss” is a review article that looks at a variety of diet studies to evaluate the effectiveness of two methods of dieting. The first method is traditional calorie restriction, limiting the total number of calories eaten each day anywhere from 15 to 60% of normal intake. This was indirectly compared to IF, which is alternating days of eating as much as you want with days of eating nothing or very little (up to 25% of normal caloric intake).
The review study by Varady found that the two methods were equivalent in the amount of weight lost (in pounds). The cool part was that the IF regimen preserved lean muscle mass much better than the traditional diet. People on the traditional caloric restriction diet lost 75% of total weight lost is fat and lost 25% of the weight in fat-free muscle mass. The IF dieters lost 90% of the weight from fat with only 10% of the weight loss coming from lean muscle mass. This is incredibly important as the lean muscle mass makes up the majority of our basal metabolic rate (BMR).
BMR accounts for >80% of all calories burned every day and is colloquially called the “metabolism.” So you can see how traditional dieting is almost shooting yourself in the foot, for every 10 pounds lost 2.5 of that is lean muscle mass. With that lean muscle mass, BMR and “metabolism” drops, making you eat even less calories to loss weight further. IF allows you to lose weight while maintaining BMR and metabolism.
In addition, people reported that it was “easier” to follow the IF diet and having a day to eat until full was better than tea-totalling each and every day. I can agree that it is much easier for me mentally to just have one day to eat what I want and then take a day off. It is much easier for me on diet days to know that I’m not eating rather than trying to eat only a little bit of something. Finally, I think IF is in concordance with how our bodies and minds were made to think about food. Humans and other omnivores were made to go periods without eating, hence the liver and gluconeogenesis. I feel zeroed in and sharp on IF days and it helps me concentrate.
The authors do not suggest why IF may preserve lean muscle mass in the article. I suggest it may be the action of glucagon, lipoprotein lipase, and the activation of glycogenolysis. A 24 hour period will not put you in ketosis, burn muscle for fuel, or result in a significant cortisol spike. I think a day without food is perfect for stressing the system just enough to put you back in metabolic homeostasis while honing insulin sensitivity. In addition, the refeeding window that occurs every other day probably plays a large role in maintaining muscle mass because the calorie deficit is not constant, allowing the necessary repair/reload of muscular tissue to occur on the ad libitum feeding days.
I encourage everyone to try IF if you are trying to lose a little winter weight, I would be interested to hear if you find it easier than dieting on a daily basis.