Comment by bsder

> I always feel there are some methodology issues in sports science studies like small sample sizes or strange metrics.

The calorie stuff is from both oxygen and deuterated water studies. You burn the same amount of calories and your system just shunts them around. The science on this is one of the few things in nutrition that is quite solid.

This has the effect, for example, that if you exercise a lot, this actually suppresses your immune system making you more likely to get sick.