[strken]

What's severe caloric restriction mean, here? From memory I've read that 750kcal and even 1000kcal under TDEE are effective. A TDEE of 2400kcal would be normal for a young 6'2" male who does a bit of light cardio, and 2150kcal wouldn't be unusual for someone who's sedentary.

[arcticbull]

Some studies, including one that followed The Biggest Loser contestants [1] showed that your basal metabolic rate goes down as much as 23% as a result of significant caloric restriction and remains lower for at least the 6 years of the study - even if the weight is regained. For these contestants the restriction was very significant, though I'm not sure if it's quantified in the study.

Here's another interesting one. Check out the Energy Expenditure section of [2].

> The gross BMR decreased in all the subjects during semistarvation, the average decline being 17.1% after 19 days (54) and 21.4% after 13 days (55). [3]

Based on this data, I would expect your BMR to go down by 20% over a period of three weeks, and remain there for the rest of your life were you to continue this for a while. So you'd have to, as an 'average' person, reduce intake by 500kcal to account for metabolic adaptation, then another 500kcal to lose 1lb per week.

That aligns with your suggestion that 750kcal-1000kcal reduction should show results for most people.

[1] https://pubmed.ncbi.nlm.nih.gov/27136388/

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3673773/

[3] https://journals.physiology.org/doi/abs/10.1152/jappl.1958.1...