another TDEE & BMR question.

dahlialia

Let's say my TDEE is 2200 and my BMR is 1600.

What exactly is the difference between eating at BMR to lose weight (1600 calories, so a 600 calorie deficit from TDEE), and eating below BMR (say 1200 calories, a 1000 calorie deficit from TDEE). Why is it healthy for my body to make up the 600 calorie deficit through burning fat (and likely some muscle), but not healthy to make up a 700, 800, 900, or 1000 calorie deficit?

What is known about the body's ability to burn fat for energy as opposed to muscle? I'm having a hard time seeing how the amount of fat we can burn could be tied to BMR. Why is BMR a magical number to not go below?

yarwell

What is known about the body's ability to burn fat for energy as opposed to muscle? I'm having a hard time seeing how the amount of fat we can burn could be tied to BMR. Why is BMR a magical number to not go below?

Excellent question.

I've read studies showing how lean mass can be preserved by eating enough protein on very low calories, and how resistance training can help with that. Until looking at the forums here I had never heard of this "eat your BMR" concept and I've read a lot of stuff about weight loss.

If you eat 100 cals less than your BMR then you'll use 100 cals more fat from adipose tissue than at your BMR.