Would like to add a few things to these tweets myself:
- It's moderately well-accepted that fasting for short periods such as 8-23 hours in humans is not at all metabolically equivalent to fasting for longer periods such as 1-7+ days in humans. I'd personally believe you could get some interesting (potentially beneficial!) effects by fasting for a week here and there due to mTOR, but we're obviously lacking the level of evidence we'd want to confidently make this claim. Regardless, intermittent fasting can help in other areas, so it doesn't mean it is useless.
- As is always the case, there's some other studies to consider: for example this one a few days ago that showed (in mice!) that fasting periods specifically were what drove lifespan increases, and that caloric restriction without any change in diet schedule did not improve lifespan: https://twitter.com/LammingLab/status/1450121276270514181 (many studies 'accidentally' combine both of them and end up with a partially confounded result. there's also some literature contrary to this, but it's an additional data point).
- As far as fat loss goes, there's some papers that show that intermittent fasting (that is, alternate-day fasting in this case) is worse than eating daily(a recent summary of one from Peter Attia: https://peterattiamd.com/is-alternate-day-fasting-superior-t...). This study precisely manages calories in participants, so one reason this could not apply to an individual is that eating patterns obviously influence how much you eat and of what.
- One of the best points from this thread is that translating results from mice to humans is hard and nontrivial, and there's many reasons for this that go beyond the obvious fact that, well, they're very different organisms. Similar to how translating the proper dose of a supplement may be difficult, translating the time period(s) of various effects and interventions is also difficult!
My takeaway as usual is that science is pretty hard, so exercising healthy skepticism is generally the right option, especially in areas that involve nutrition/diet/biology, since this is even harder than many other areas of science.