you know that isnt a real thing right? just like the supposed links between sodium intake and blood pressure, and saturated fat intake a heart disease.
There is a difference between fasting techniques. What he wants to do is not eat any foodstuffs for an entire week and only drink water. That will, in fact, damage your metabolism and often results in over-eating after the fasting.
2 months ago I water fasted for over 10 days. after resuming eating I gain some temporary water/food weight, and got right back on track to my ~2lbs/week weight loss. starvation mode isnt a reality, and fasting is very sparing of your metabolism. so long as he has enough body fat, an extended fast (when done properly) is of no real risk to him.
More than three days starts cutting into muscle mass bro, which is why my longest fast was only 2.5 days.
You lift brah? Your numbers get hit at all?
Explain this to me: Our bodies are pretty well designed to try to stay alive. We store up fat for this very purpose, so then why would our bodies as hunters and stuff start eating away at our muscles before the fat? The whole fucking point is that hunters could survive a while between hunts if they had built up fat reserves. A water fast is doing exactly what the body is designed for: Burning fat and mostly keeping muscle during a period where food cannot be found.
It would not make sense for us to develop such that the first or major thing we burn when not finding food is muscle.
Right?
That's why I said after three days, the body primarily burns fat but also starts burning muscle.