I actually do think it's pretty much as simple, for most people, as counting calories and determining approximate usage. Is it exact? No...but it's close. There's some fluctuation as far as water weight
yeah, calories ... activity.. the formula is simple. But the reason it does not work for many is because there is the psychological factor involved. When you are near a lot of food all the time, everywhere, calorie dense, *cheap* food, it's hard to resist. Starbucks has calories in it, various fast food joints, sometimes you are given free pizza..
call it peer pressure