This probably comes up a lot here, sorry for the new thread if it's too redundant, but I have been continuing to poke around, and found that fitday thinks I use 2600 kcal/day for BMR+'lifestyle', while my wife's nutrition text says that for my age and height, a person w/ bmi=22.5 (I'm around bmi=24) would use 3000 kcal/day (maybe it's assuming that maintaining that bmi implies a certain level of activity?). Anyway, both of those seem insanely high to me. My wife hasn't looked at fitday yet, but the text thinks she is using 2400 kcal/day to break even and that is very far above her estimate of what she can eat and avoid gaining weight, never mind losing it (weight watchers allows her ~1100 kcal/day to lose weight).
I know there is a *lot* of underestimating of what we eat, but it's scary to think that we could be underestimating what we eat (when not losing weight) to cancel or even exceed those levels of baseline calorie requirements. So we naturally assume the estimates must be off.
those numbers are ball park figures, really. Everybody is different so that's where keeping a food log to track what you are eating comes in handy. You have to maintain your weight and see how much you are taking in. Obviously, the more data points you have, the more accurrate you will be. Make sure you aren't letting hidden calories into your diet. Good luck
The formulas you see have bunches of assumptions. Also it would be fiendishly difficult to calculate a person's caloric requirements per day based on activity. Some people fidget all the time and get up and move around and never sit still. So even though according to the lifestyle questions, they look pretty sedantery, they really are not. Another person could have a daily work out routine but relax the rest of the time and actually burn fewer calories. The formulas are just rough estimates and nothing more.
when using fitday you need to do a couple things to get a somewhat more accurate number. first, choose sedentary as you lifestyle as the other options greatly inflate the daily burn total. second, you must account for sleep as you body burns less while sleeping. fitday does not adjust for sleep automatically so you have to enter it as an activity.
using my approach above, i entered only activities that were strenuous in nature, such as workouts, rides, running, and skipped other stuff like walking around the mall or driving. i entered all my foods, most were custom entries. so i had my basic daily needs and pretty much my exact daily intake. the numbers and the results showed me burning more then taking in. i did this for one year and dropped 66 pounds.
the numbers must have been in the ballpark! i'm not saying, i'm just saying. later.