The general concept is to burn more than you intake. Our bodies at rest will burn a certain amount of calories just to keep functioning going. This is our BMR (basal metabolic rate) or RMR (resting metabolic rate). They are calculated with two different formulas, but seem to give about the same results.
Notes on BMR/RMR
- As we get older our BMR/RMR decreases.
- BMR/RMR does not account for body composition. More muscle = more caloric burn.
BMR/RMR Calculator
Added on top of RMR is the calories we burn in activity for our total calorie burn.
RMR + Daily Activity = Total Burn
Calories consumed - Total Burn = Deficit or Gain
3,500 calorie deficit = 1 pound of fat lost
Theoretically that is how it is supposed to work. The difficulty comes in getting accurate numbers. Since body composition is not taken into account your RMR could be inaccurate. We end up losing muscle in our efforts instead of fat which lowers our RMR. Determining how many calories we burn through activity can be difficult to really measure. We can sometimes misjudge and misrecord our caloric intake.
So we all often look to our personal results and tweak our plans. What we would like to be an exact science becomes more like a observational study. But counting our calories and tracking our activity does give us some data to work from.
One thing that can help to determine how accurate your numbers are is reverse math. Let's say you know you burned 7 pounds in a month.
3500 x 7 = 24,500 caloric deficit
In that time you consumed 45,000 calories. (1,500 calories per day x 30 days)
24,500 deficit + 45,000 calorie intact = 69,500 caloric burn
69,500 calories / 30 days = 2,317 avg caloric burn / day
I would then check this against what is being estimated as total daily burn and take into account that the more you lose the less your body burns at rest.
You seem to be getting amazing results! Crunch your numbers, but if you are getting success that is all that really matters right?