Understanding RMR, BMR and more for weight loss

You bought the best home treadmill.

You carefully considered where to place it for optimal usage.

You started walking, then running and the weight was slowly coming off!

Then suddenly it came to a screeching halt! Wondering if you need to workout more? Eat less? Maybe you’ve actually hit your best body weight…let’s look at some of the numbers that can help you decide what to do next.

BMR and RMR

Basal Metabolic Rate and Resting Metabolic Rate are the two most common terms that you might hear about when determining how to calculate calories. There is a slight difference in the two and it’s important to know which you’re using. There is a slight difference in the two and it’s important to know which you’re using:

BMR: An estimate of calories burned if you truly laid in bed all day. It accounts for only bodily functions (breathing, etc). Below is an image that shows the general BMR for males and females throughout their lifetime.

Image Credit: fao.org

RMR: An estimate of calories burned if you laid in bed all day, but also drank water, ate meals and small activity like moving to the bathroom.
The Harris-Benedict equation for BMR:
For men: (13.75 x w) + (5 x h) – (6.76 x a) + 66
For women: (9.56 x w) + (1.85 x h) – (4.68 x a) + 655

The Mifflin equation for RMR:
For men: (10 x w) + (6.25 x h) – (5 x a) + 5
For women: (10 x w) + (6.25 x h) – (5 x a) – 161

Where:
w = weight in kg
h = height in cm
a = age

In most cases, people will take their RMR + calories burned during exercises to determine the total calorie expenditure for the day. After finding this, the long held wisdom has been that to lose weight you simply need to keep your calories below this threshold. If all of these calculations are making your head hurt then head over to Shapeup.org where you can use their cool RMR calculator tool.

GETTING AN ACCURATE TEST

While both calculations can get you close, an in office test will get you even more accurate results to help with weight loss. Since a BMR test requires an overnight stay in a lab, let’s focus on the more accessible RMR test.

An RMR test has you sit comfortably with a mask that covers your nose and mouth allowing you to breathe normally. The machine measures CO2 to calculate your results. For most accurate results you need to fast for 12 hours prior to the test and do as little activity as possible.

CALORIES BURNED

After getting your RMR results, it’s time to calculate calories burned on that treadmill! While all treadmills come with built in calculators, it’s been reported that these numbers can be up to 30% higher than actual calories burned.

Treadmills with an integrated heart rate monitor will be more accurate as they are based on how hard you are working, rather than the estimates of a 150lb male. We know it is not an exact science using some of these methods but by using this as a guide they can get you close to finding your RMR / BMR.