BMR confusion

U

unreal23

New member
Hi everyone,

I recently purchased a calorimeter which straps around the forearm and measures heart rate, as well as calories. I inputted my age, weight, gender, height and RHR. The device indicating about 2 calories / min burned just sitting around the house. This would mean around 3000 calories daily I burn doing essentially nothing. Is it possible my metabolism is so fast that I burn this much daily? I am moderately active doing cardio and weights 4-5 times a week...but I still wouldn't expect to burn 3k calories in 1 day just sitting at home!! BMR calculators online indicate around 1800-1900 calories depending on the formula I use. Thoughts?

I am 31 male, 5"10-5"11, around 180 lbs. LBM around 140 lbs.
 
BMR and maintenance are not the same thing - people get them confused.

BMR is what your body needs to survive if you did nothing but lie in bed all day and breathe. Your maintenance calories are your BMR calories multiplied by an activity factor to allow for your daily activities - everything from moving around, showering, walking around, any exercise you get, etc.

At 180 lbs, it's entirely possible that your maintenance calories are around 2800-3000. A good estimate is to multiply your current weight by 15 or 16 (if you're a man) or 13 or 14 (if you're a woman). That should give you your MAINTENANCE (not BMR) calories.
 
A calorimeter is a laboratory device for measuring the heat of a chemical reaction. You are indeed trying to measure the heat of a chemical reaction, metabolism, but I think that the device you have is probably just a heart rate meter. There is a fairly crude relationship between heart rate and metabolism, but I wouldn't put a whole lot of faith in the accuracy.

There is another device called a bodybugg which measures additional parameters like skin temperature, acceleration, etc. That's more accurate, but I prefer the old fashioned method. Watch the scale and see if you are losing weight.
 
Kara,

Where do is a good resource to get the activity factors that mention above. Also I am assuming that you would want to aim your calorie intake below the maintenance level not the BMR level. Although being below BMR might be a more sure fire way of losing weight.

Frank
 
I am assuming that you would want to aim your calorie intake below the maintenance level not the BMR level.
Click to expand...
Pretty much - although at some weights it's impossible to not drop below BMR - if you're extremely overweight, your BMR is inflated due to your excess weight, so going below it won't be harmful - and for some people you'll see a faster weight loss which is more inspiring to keep going. And women too ... it's hard to not drop below BMR when you're already fairly small and need to lose those last few pounds. Overall, though, at your height/weight, the bottom line is that you really don't want to drop more than 20% - 30% of your calories total, though, or you risk stalling out your weight loss.

The most commonly used figure to get your BMR is the Harris-Benedict equation. The one for men is:
66 + (13.7 x weight in kilos) + (5 x height in centimetres) - (6.8 x age in years)

The activity multipliers are:
1. If you are sedentary (little or no exercise): BMR x 1.2
2. If you are lightly active (light exercise/sports 1-3 days/week): BMR x 1.375
3. If you are moderatetely active (moderate exercise/sports 3-5 days/week): BMR x 1.55
4. If you are very active (hard exercise/sports 6-7 days a week): BMR x 1.725
5. If you are extra active (very hard exercise/sports & physical job or 2x training): BMR x 1.9

So inputting your numbers from your first post I get:
BMR = 2100
Maintenance = 3255
Pretty close to what you go with your device.

Keep in mind that all these numbers are estimates. Everyone is different and no one burns the exact same amount of calories every single day. If you sleep in an extra 15 mins, you'll burn fewer calories. If you walk to the bathroom 3x a day instead of 1x, you'll burn more. Etc. You have to allow for a 10% or so variance from day to day - which is why it's really important not to get hung up on the numbers too much.

Start with dropping your Maintenance calories by, say, 20% and see if you start losing weight (for you that would be 2604 per day). If after a few weeks, you're not seeing results, then drop it to 30% (or 2279 per day).

Also keep in mind that a safe and healthy rate of loss should be about 1% of your overall bodyweight per week. So if you weigh 180, then you should expect to lose about 1.8 lbs a week. If you're being healthy about it.
 
Kara,

Excellent post

frank
 
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