You see I eat quite alot. But at the same time, like today, I race walk a half marathon- most every day. So you have to subtract off the energy expenditure during that time plus also subtract off the weight of the sweating I do during those 3 hrs of racewalking.

It's a difficult calculation but my estimation is that 50% of what I take in comes out as waste products, in round or elongated numbers of course.

yanniru