I've toyed with this idea before but the truth is that I'd rather guesstimate my overall activity level. I have no way of knowing exactly how many calories I do indeed burn during any given exercise because I feel I may overestimate my effort -- and like I said, I feel like I've adapted to certain things that I do, like walking to class or working, thereby becoming more efficient at burning calories and thus burning less. And like, when I lift weights, I probably log time spent in the gym instead of time spent actually lifting. I've read a couple opinions from both sides of the spectrum and currently calculating activity level makes more sense to me, but I suppose I can always know more! Once I get through this slog-fest of homework I'll look up some articles. EDIT: Wow, it seems a lot of people have the opposite perspective from me! Care to share why?