Thread by @nicknorwitz

1/ Interesting study comparing the metabolic effects of #fasting: lean vs. obese ppl

👉Lean have greater ⬆️ in Lipid Oxidation (+214% in lean vs. + 76% in obese at 48 hrs)

👉Resting energy expenditure ⬇️ in obese only

👉Skeletal muscle AMPK ⬇️ in lean
pubmed.ncbi.nlm.nih.gov/23512807/

2/ Points 1 and 2 go in line with what I'd expect. Leaner metabolically healthy people probably have greater metabolic flexibility, resulting in better shift to fat burning. But point 3 about AMPK surprised me. Here's why...

3/AMPK is the cellular energy sensor. It's activated, in part by low energy status, i.e.

Decrease cellular energy supply increases AMPK activity

Seems paradoxical that in lean persons who r fasting AMPK activity goes DOWN, not UP, as if there is more energy when taking none in

4/ "Surprisingly, AMPK-Thr172 phosphorylation, which was not different between groups at baseline, was reduced by fasting in lean but not in obese"

5/ Then in the discussion the speculate that this could be due to increased glycogen stores during a fast!!! Isn't that odd?!

I find that interesting because I actually find I have a lot of power after a fast, e.g. I could more easily do muscle ups clap push-ups etc. That's n=1

6/ There is further interesting speculation as to mechanism/rationale & I encourage people to read this paper. Fun!

But one think I will point out is the they only looked at skeletal muscle AMPK. I'd bet you'd see VERY different things looking at fat cells and liver cells.