# Question for Brock or FF vets

How do calculate BMR for fat fast? I didn’t see a formula in the two original articles. In the female fat fast article, the formula says to use some operations involving bodyweight, but doesn’t say whether to use kilograms or pounds. I also presume that, when possible, you should use just your LBM when doing these operations. I never calculate my full bodyweight. Help!

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Depends on how much weight you have to lose. I would calculate your caloric needs (massive eating part 1), then determine how many pounds of fat you need to lose. Then determine your time frame and eat just enough so that you can lose the fat.

For example, you calculate your caloric needs - approximately 4000 calories on training days and 3000 on non-training days.

You have 8 weeks that you will do the fat fast.

You want to lose 20lbs of fat.

Each pound of fat is requires 3500 calories to burn, so you need to create a total calorie deficit of 70,000 calories over 8 weeks. This works out to be a 8750 calorie deficit a week or a 1250 calorie deficit a day. This should probably be upped to 1300-1500 due to a drop in RMR and your ability to keep up the activity.

Wow, as I write this I realize that you could try to do this in a shorter time frame like 6 weeks at 1667 calorie deficit a day. Once again, probably should be bumped to 1800-2000 cal deficit a day.

Of course this was just my suggestion. Brock did not specify, so this was the best solution that I could come up with.

Brock explained this in one of the paper issues in which the FF articles were reprinted. If I could’ve found the issue, I would’ve posted it for you. However, as a FF vet, the shortcut method is to take your body weight and multiply it by 11. Afterwards, divide by 2. Example: 180x11=1980 calories. 1980/2=990 calories. When I did this against Brock’s formula, I didn’t find much of a difference. Don’t be anal about it. Just get a reasonable number and work with it.

thanks for the help