Hey there, I’ll make an educated guess that you have read the post I wrote some time ago in which I said that intermittent fasting is no better than continuous calorie restriction for weight loss:
And boooy how I pissed off people who like having air for breakfast aka intermittent fasting extremists.
Some ignored the weight of the evidence and kept believing that intermittent fasting is the best thing ever.
Some were more intelligent and said “Yeah, maybe intermittent fasting isn’t better than continuous calorie restriction for weight loss but it offers many other health benefits. Autophagy and stuff, you know.”
And so now I am about to piss those people off too (things like that definitely reduce the size of my circle of friends) because a new systematic review and meta-analysis by Chen et al. (2021) found that if you don’t do fasting, you are probably not missing out on much in terms of health:
Ok, let’s pause for a second here because I want you to understand that a systematic review and meta-analysis is not “just another study.” It’s an unbiased way to determine what the science says “on average”:
Anyway, the researchers found that there were no significant differences between intermittent fasting and continuous calorie restriction. Most improvements in health markers were similar.
Intermittent fasting caused lower blood pressure and fasting insulin levels (but not blood sugar). However, it increased LDL cholesterol levels (it’s bad). Also, it caused the loss of lean mass (also no bueno and which is why I said you should probably avoid long fasts).
Earlier high-quality evidence such as this meta-analysis:
Also found that intermittent fasting and continuous calorie restriction offer equivalent outcomes in terms of weight loss and health markers—improvements in glucose control/insulin sensitivity, thyroid, cortisol, and sex hormones were similar in both diets.
Although, intermittent fasting suppressed hunger better (it’s not bad, it’s great).
The researchers concluded:
I don’t doubt that after reading this, heaps of people will wonder why is this? Why intermittent fasting doesn’t seem to improve health markers more than continuous calorie restriction considering all the hype?
No worries. I’ll tell you why:
It’s due to weight loss. Naude et al. (2014) estimated in their meta-analysis that most, if not all, health benefits happen simply due to the lost weight itself rather than the diet type.
At this point, some intermittent fasting zealots will become so angry that their teeth will start to fall out. Right before the last tooth comes out, they will mumble something like “Hey, you caveman, ever heard about autophagy? Intermittent fasting causes your body to “self-eat” damaged organelles in the cells which increases longevity.”
That is 100% correct (assuming a calorie deficit) but what they don’t know is that autophagy isn’t fasting-specific. It happens in any diet that puts you in a calorie deficit. Autophagy is the result of calorie restriction, not fasting (Anton and Leeuwenburgh, 2014):
Listen, I’m not trying to shit on intermittent fasting. I’m trying to shit on people who tried fasting, liked it, and now they assume everyone else should do it based on pseudoscience.
As Jeremy Clarkson once said:
Multiple studies have demonstrated that intermittent fasting can be an effective tool to create a calorie deficit and, therefore, lose weight. It can be as effective as continuous calorie restriction.
If you find intermittent fasting sustainable, can be consistent with it, it doesn’t take over your social life, it improves your relationship with food, and allows you to make progress, there is nothing wrong with it.
But it’s not magic.
Originally published by me on Medium on November 9, 2021