Your BMR

[Dr Game]

I'm more or less wondering this.

I know everyone's BMR calculation is different, and in theory the calculation performed is an approximation.

What I am wondering is lets say you weighed 250 lbs, and lost 50lbs down to 200lbs.

The BMR you had at 250 and 200 lbs is different. Now lets say you gained back 50lbs, but it was all in muscle. Would you still have the same BMR as you did originally when you had 250lbs?

If not, how does fat percentage come into play, and if it does, then why don't BMR calculators take it into account?

 

[Steve]

Fat and muscle have different metabolic rates.

 

[maleficent]

I think that's h is question though -

Kind of like BMI doesn't take into consideration muscle -just weight and height -

BMR doesnt seem to take into consideration muscle - just age/weight/ height -and shouldn't it?

 

[Dr Game]

Fat and muscle have different metabolic rates.

That makes sense to me, so I'm wondering why calculators don't even attempt to put that into considertation to give a closer estimate.

 

[[Focus]1]

That makes sense to me, so I'm wondering why calculators don't even attempt to put that into considertation to give a closer estimate.

There are a number of formulas that utilize fat free mass, if you happen to know it. The reason is that most people are either unaware of or incorrect about their body composition percentages.

One simple one (it's the same for men and women) is:

BMR = 1.3 * Fat Free Mass (in kg) * 24

This will generally give you an increasingly greater total expenditure than the standard Revised Harris-Benedict formula as your body fat moves away from 30% (in the direction of less than, naturally).

Please keep in mind that this number also reflects your basal metabolic rate and is not adjusted for activity level (which is of course the second part of the equation).

Activity Multiplier
Sedentary = BMR X 1.2 (little or no exercise, desk job)
Lightly active = BMR X 1.375 (light exercise/sports 1-3 days/wk)
Mod. active = BMR X 1.55 (moderate exercise/sports 3-5 days/wk)
Very active = BMR X 1.725 (hard exercise/sports 6-7 days/wk)
Extremely active = BMR X 1.9 (hard daily exercise/sports & physical job or 2X day training, i.e marathon, contest etc.)

 

[Steve]

What focus said.

But it all goes back to not being so nit-picky wrt to determening caloric requirements.

Pick a number for intake using any of the calculators. Track progress. Adjust as needed.

 

[Dr Game]

One simple one (it's the same for men and women) is:

BMR = 1.3 * Fat Free Mass (in kg) * 24

This will generally give you an increasingly greater total expenditure than the standard Revised Harris-Benedict formula as your body fat moves away from 30% (in the direction of less than, naturally).

I don't entirely understand this part, are you saying someone with 30% body fat uses the number 1.3? Therefor someone with 20% would use 1.2? And so on...?

 

[[Focus]1]

I don't entirely understand this part, are you saying someone with 30% body fat uses the number 1.3? Therefor someone with 20% would use 1.2? And so on...?

No, the formula is always the same. The rest of what I'm about to say isn't important, it's just an observation, so ignore it if it's confusing.

The Fat Free Mass formula will return a higher basal metabolic rate (more calories needed to maintain weight) for persons with a higher percentage of lean mass relative to fat mass, the cutoff for which is 30% body fat. This means that people with body fat greater than 30% will find this formula estimates their BMR at a lower number than (the standard) Revised Harris-Benedict formula. Conversely, for persons with less than 30% body fat it will estimate a higher caloric need than Revised Harris-Benedict (all other factors - height, weight, gender, etc - being equal).

 

[Dr Game]

Okay, thank you, I understand. That is some good information.