Difference between BMR and REE

BCSMama
BCSMama Posts: 348
in Health and Weight Loss
So, last year I participated in a weight loss study at the university I work at and they did tons of cool testing. Since I've joined MFP, some of the test results make a little more sense to me than they did back then. I hear a lot about BMR here and have a pretty good idea of what that means; the number of calories you body needs for basic functions if you were basically in a coma. However, one of the tests they did was REE (Resting Energy Expenditure) where I was completely still in a bed with a big bubble around my head and some monitor in my foot I think measuring respiration and pulse. The definition they gave is: the required amount of calories your body burns to maintain normal function while lying down. Sounds pretty similar to BMR to me. However, when I go online to calculate my BMR, it's way higher than the REE results I got, which were:

33 year old female 5'10"

Starting weight 189.2 - REE: 1785.6
Ending weight 169.6 - REE: 1304.4

If I go to a BMR calculator and enter my stats from a year ago at 169.6, I get a BMR of around 1550, which is higher by like 250 calories. If I calculate my BMR now at 147, it's around 1450, so by my way of thinking, my REE would be like 1100, right? I believe the REE is obviously more accurate for me since it was calculated with such extensive testing rather than a web calculator. So, when people say to eat above BMR, is that interchangeable with REE? According to some online calculators, my TDEE is currently around 2500, which seems to leave a huge gap.

Anyway, I guess my question with all of this is what is the difference between BMR and REE and why is/was my REE so much lower than my BMR?

Replies

  • GoatBoat66
    GoatBoat66 Posts: 56
    Your BMR is always going to be less than your REE, by definition. The BMR calculator you used was inaccurate.
  • psuLemon
    psuLemon Posts: 38,428 MFP Moderator
    What goat says.. BMR is the amount of calories you would burn if you were in a coma. Also, many online calculators don't account for body fat % (which will help make it more accurate). If you have less muscle as compared to the equivalent person your size your BMR will be lower. If you have more lean body mass than the average person, then your BMR would be higher than the average person your size.
  • Mokey41
    Mokey41 Posts: 5,769 Member
    The BMR calculators are just using general stats for the population. You're lucky that you actually had the testing done so you know for sure what your rate is. Most of us don't have access to that type of testing. It just goes to show that all the calculators and numbers are really only wild guesses.
  • BCSMama
    BCSMama Posts: 348
    Your BMR is always going to be less than your REE, by definition. The BMR calculator you used was inaccurate.

    Yeah, that's what I thought. I guess it just surprises me then that my BMR would apparently be so low for someone my size. If my REE when I was 20 lbs heavier was 1304, it's probably less than 1000 now, meaning my BMR would be even less than that! That just seems so low for someone 5'10" and 147 lbs.

    So, any advise on how many calories to eat to loose around .5 lbs per week based on that? I do exercise 5 days a week (3 x basic training resistance/strength type class and 2 x running about 5K).
  • geekyjock76
    geekyjock76 Posts: 2,720 Member
    Resting Energy Expenditure is synonymous with Resting Metabolic Rate, which is the amount of calories burned at rest in a 24 hour period. It is one of four components of your TDEE: the other three being Thermifc Effect of Food, Thermic Effect of Activity and Non-exercise Activity Thermogenesis. In regards to TEF, it roughly consumes approximately 10% of ones TDEE so you'd add 10% to REE or RMR. If you accurately measure TEA, you would add that. NEAT, however, can be very small for one who is sedentary outside of planned exercise and can contribute to perhaps another 10% - or it can be quite significant if one has a physically demanding job. Thus, even with this approach, you will be just as off potentially as using TDEE formulas.

    Your best solution in establishing the proper deficit is to exercise as you presently are and consume the maximum amount of calories where you maintain your body weight. Keep in mind maintenance is not the same as experiencing a plateau, however, if you've been assuming an energy deficit. Once you have sufficiently upped calories and you are able to maintain weight for a month, then you can take a cut of about 250 below that number to lose "approximately" 0.5 lbs per week.

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