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- Intermittent Fasting
Intermittent fasting is a popular tool in the health and fitness community. We kick off this episode of the podcast/newsletter with a question that Jason got on Twitter. It is a common question we will get and it always goes something like “What do you think of intermittent fasting?”. Like most things, it has it’s time and place, but sometimes the wonderful world of the internet has a way of hyping things above and beyond reality. We decided to go through a few points regarding intermittent fasting and see what the studies say.
First of all is the big question of “can you lose weight/fat doing intermittent fasting?”. The answer is yes. Can you lose weight simply by restricting calories? Again, the answer is yes. Does intermittent fasting produce superior results in weight/fat loss compared to simple caloric restriction? The answer to this is no, according to the available studies we have. The argument in favor of intermittent fasting has to do with fasting lowering insulin levels and thus allowing you to burn more fat. The problem is we have these pesky things called human randomized controlled trials where we are able to compare the two and we don’t see see significant differences in body weight reduction or body fat reduction. Also, as we touched on in the semaglutide episode, the new weight loss drugs (Ozempic and Mounjaro) increase insulin levels and people are losing large amounts of weight.
The second point we touch on is the issue of autophagy. Autophagy is basically normal cell turnover. It involves cleaning up cellular debris and getting rid of old cells. The thought is that fasting will boost autophagy, thus keeping you healthy and boosting longevity. This is an area with a lot of fancy sounding words and nice ideas, but not a lot of hard science. Does fasting increase autophagy? We think so. Does simple caloric restriction also increase autophagy? Yes. Some cancers also show increased autophagy. Lots of things boost autophagy. So how much of a longevity increase is there? Who knows. We know caloric restriction consistently lengthens lifespan in rats and mice, and even in dogs, fish, and hamsters. The problem is human trials are a bit more complex and thus lacking. So concluding that intermittent fasting will boost autophagy and thus increase longevity is a bit of a stretch.
Finally, we touched on the issue of appetite. Proponents of intermittent fasting will say that even if intermittent fasting doesn’t produce superior results, it is easier to stick to because you won’t be as hungry. We discussed a recent systemic review and meta-analysis on intermittent fasting and appetite which concluded that there was no clear evidence that intermittent fasting affected hunger, fullness, desire to eat, or prospective food consumption differently than continuous energy restriction (caloric restriction). So to say you will feel more full and less hungry with intermittent fasting is just not consistent with current studies.
To wrap things up, intermittent fasting is a useful tool to have in the tool belt. You can absolutely lose weight and fat with intermittent fasting. It is not superior to simply reducing calories. Some people will be successful with it, other people will binge too much during their eating window and not have success with it. We do bring up our one concern with intermittent fasting which is possibly struggling to get in enough protein during the day. If the feeding window is too small, and knowing that you can only ideally absorb about 20-40 grams of protein in a sitting, it can be tough to get in 100 plus grams of protein in per day. This could possibly lead to excessive loss of lean mass while losing weight.
Simplified Takeaways…
You can lose weight and fat with intermittent fasting.
It is not superior to the loss of weight and fat that you would get with simple calorie restriction.
Studies show that feelings of hunger, fullness, and desire to eat are about the same between intermittent fasting and simple caloric restriction.
Be sure to get in enough protein if you do decide to do intermittent fasting. This can be a challenge if your feeding window is too small.
Further Reading…
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