[lin43]

I've read that you shouldn't eat below your BMR calories for various reasons (you'll lose muscle, you'll lower your metabolism, etc.). I'm trying to figure out the calories I should eat, and I don't know whether I'm supposed to base that on my current BMR or my goal weight BMR. My BMR for my current weight is 1442. The BMR for my goal weight is 1260. Any thoughts on this?

[Esofia]

What are your height, weight, and current calories burned?

[JohnP]

Amazing the crazy stuff we can read out there.

None of that is accurate.

Your metabolism is going to slow down when you diet. How much and how fast depends on a variety of factors but at most it will probably not slow more than 10-15%.

Muscle loss happens when protein intake is inadequate and muscles are not used.

You can also lose muscle by too heavily restricting calories over too long a period of time and a huge amount of this depends on how much fat you have.

[lin43]

Thanks, John. How long is "too long" (estimated) and how low is "too low"? I guess my last question here pertains to my original question.

Esofia, I plugged all my numbers into a web site (recommended by a few people) to find out the BMR numbers I quoted above.

[JohnP]

Originally Posted by lin43

Thanks, John. How long is "too long" (estimated) and how low is "too low"? I guess my last question here pertains to my original question.

You're asking an extremely complex question but the very simple answer is that the more fat you have the longer you can restrict calories massively without muscle being catabolized assuming protein intake is sufficient.

It comes down to energy. The energy needs of the body must be met. If the body can't meet them from fat it will take what it needs from muscle.

Also the body adapts. If you're not using muscles you will lose them and you'll lose them faster when dieting.

Bottom line is most people don't need to worry about this because they have plenty of fat to meet the energy needs of the body.

Just use your muscles and get adequate protein. If you get adquate protein you're probably also going to be getting enough calories because most people aren't going to want to eat meat only.