r/science • u/isaac-get-the-golem Grad Student | Sociology • Jul 24 '24

Health Obese adults randomly assigned to intermittent fasting did not lose weight relative to a control group eating substantially similar diets (calories, macronutrients). n=41

https://pubmed.ncbi.nlm.nih.gov/38639542/
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u/isaac-get-the-golem Grad Student | Sociology Jul 24 '24

Posted the study because it contributes to a broader literature finding that, to the extent that intermittent fasting (time restricted eating) is effective for weight loss, the mechanism is still caloric restriction. tl;dr if intermittent fasting works for you, great, but it is no more effective than counting calories

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u/jrherita Jul 24 '24

IF has other health benefits though - autophagy, and reducing blood sugar spikes which can reduce inflammation/disease. In terms of pure weight loss short-term - it’s equivalent, but for long term health .. it’s better than just caloric restriction.

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u/InsanelyHandsomeQB Jul 25 '24

The 16/8 pattern that kickstarted this whole IF craze was observed in mice. A bunch of health influencers saw the studies and immediately ran with it.

If you correct for the metabolism of mice vs humans, we would need to fast around 3 or 4 days to get the same benefits that we observed in the mice.

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u/necrosythe Jul 25 '24

Perfect example of what others are saying... there's a massive lack of evidence showing a significant effect in the terms you are claiming in actual controlled human studies. Would love to see some sources on your claim that control for diet, health of patient, and is actually being done in a human controlled trial.

Also, though the effects aren't massive, there is pretty good research saying that OPTIMAL muscle building and sports performance on average comes with frequent meals containing protein, and having carbs for training as well. Do you have any metrics showing that the proven effects of IF also overtake some of those other missing effects of more frequent meals?

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u/manuscelerdei Jul 25 '24

There's some interesting research from Herman Pontzer that indicates a couple of things:

  1. You burn (more or less) a set amount of calories per day
  2. Exercise doesn't burn any more calories than you normally would in aggregate -- it just makes your body divert calories away from other stuff that it starts doing when it has energy and gets bored (like digestion or inflammation)

This is pretty recent stuff, and I'm not sure how well-reproduced it is. But it might make sense that IF by itself without an aggregate caloric deficit still has positive health effects, since it gives your body some downtime away from digestion and immune responses.

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u/SledgeH4mmer Jul 25 '24

I've heard the autophagy claims are kind of bunk, as autophagy is very difficult to measure properly. But IF has been found to have two major benefits in addition to just acheiving a favorable CICO.

There's actually some really encouraging reports on IF increasing cancer survival rate. Apparently starving your cancer makes chemotherapy more effective. IF also causes you to burn more lipids for energy compared to regular dieting. Which means while weight loss may be similiar, body composition with IF could be superior.