Active Low-Carber Forums - View Single Post - Any large scale studies showing the benefits of fasting?

Cahill had one study in normal weight divinity students, eight days into a fast their daily calorie expenditure is given as about 1100 calories a day, of course this is going to be with very low activity levels but still even basal metabolism would have been at least 500+ higher when these guys in their twenties weren't fasting. Also when numbers are given in various studies by Cahill estimating glucose vs. ketone vs. free fatty acid use during long fasts in obese subjects, the figure I see for total calorie expenditure is 1600 calories, and given that usually basal metabolic rate is higher in obese subjects than in lean, this probably does represent a substantial drop in metabolic rate.

The data used to show that fasting doesn't drop the metabolic rate, from what I've seen, looks at the first 48 hours or so. Yes, metabolic rate can increase early on. No, it doesn't remain high.

https://www.ncbi.nlm.nih.gov/pmc/ar...a00095-0049.pdf

Quote:

A decrease in metabolic rate has been noted in starvation for decades,
having been extensively studied by Dubois, Benedict and others. Part of
this is explained by the progressively decreasing lean body mass, but the
energy decrease appears to be more than accounted for by decreased
metabolizable mass. The selective use of fat as fuel, everything else being
equal, would be expected to increase oxygen consumption, since it is
slightly less efficient than glucose as an energy source, yet, total oxygen
consumption is decreased about 10-15 percent.

We need a comparison of like to like, refeed somebody after something like this, versus the sort of restriction that dropped metabolic rate by 40 percent in the Minnesota starvation experiment. I like Dr. Fung I think he's doing a lot of good, some of his use of the literature I find a bit iffy, he's trying to apply the "best fit" for some questions science hasn't really answered yet, that can get you in trouble. Sometimes I think he'd be better off taking a page from Dr. Westman and just saying "I don't know, but here's what happens in my patients."