Re:Perhaps it's worth investigating... (Score 1)

You don't have to. You can take a rough guess and allow for a pretty huge margin of error. For example, someone who eats whole grains, lean protein, quality fats in the form of nuts etc, and various fruits and veggies who works out at a reasonably high level of perceived effort regularly for a year WILL lose weight if what they were doing the year before was eating shit and sitting on their ass. Actually, not only will they lose weight but they'll become reasonably athletic 9 times out of 10. That person can completely ignore all the 'math' involved with calories in/calories out and just ASSUME the ratios will work themselves out, because they're doing the 'right things'. It really, actually is that simple.