Comment by bluecalm

I would like to see some answers on this one. First, why are we adjusting for lean body mass? I mean if you're 120kg with 50kg of extra fat you will obviously burn more calories by carrying that around. Someone who doesn't have additional 50kg of fat will need to exercise to burn the same amount of calories. It's well known in fitness circles for years now. It would be surprising if lean sedentary people burnt as many calories as active ones.

The limit of 4650kcal per day doesn't sound right. A lot of endurance athletes, even amateurs, burn more than that. How much you can digest is limited (common wisdom is 60-90g of carbs per hour when exercising which is 240-360 calories). Still there are also glycogen stores for additional 1500-2000 kcal as well as your fat stores which are heavily in use during long lasting endurance effort. I assume the limit is meant for long term which would make more sense.

The fact about ultra marathoners who burnt 6200 kcal at the beginning of the race but only 4900 at the end is interesting. Assuming they weigh say 60kg then it takes around 2500kcal to run a marathon. There is a lot of other stuff going on if they burnt 6200 per day. It would be interesting to see if there aren't other information that explains the difference (like hills for example).