The average basal energy expenditure (BEE), also known as basal metabolic rate (BMR), for American women is about 1,400 calories while for a man its roughly 1,800. But don’t assume you’re average!
Your Basal Metabolic Rate (BMR), also know as your Basal Energy Expenditure (BEE) is an estimate of the energy your body uses at rest. It’s measured in a dark room, after waking, in a fasted state to ensure that it only includes the energy used during resting metabolic process.
How Important Is Your BMR/BEE?
Typically about 60% of our total energy needs come from resting metabolism (see above), but this varies greatly depending on our activity level.
The average BMR for an American woman is about 1,400 calories, while for a man its about 1,800. But you shouldn’t assume your metabolism is average, or that your needs are static.
Let me show you why with some data from the Institute of Medicine’s Dietary Reference Intakes.
Basal Energy Expenditure for Women
Earlier I said the average American women’s resting metabolism uses around 1,400 calories a day. But I don’t want you to assume you’re average!
Have a look at the data to see the variation.
On this chart each dot is a woman. You can see most women are in the 1,200-1,600 calorie range.
I’ve graphed the metabolic rates against weight here because its a better predictor of BMR than other variables like age and height. The orange line is the line of best fit. It shows that BMR generally increases with weight among women.
Now let’s have a look at men.
Basal Energy Expenditure for Men
For men I said the average American resting metabolism uses around 1,800 calories a day. But again I do’t want you to assume you’re average. Have a look at the data to see the variation.
On this chart each dot is a man. You can see most men are in the 1,600-2,000 calorie range.
Again I’ve graphed the metabolic rates against weight as it tells a story. The orange line of best fit showing how BMR increases with weight among men too.
The variation around the line is explained by differences in height, age and particularly genetics. Although we can’t explain all of this, I’ve got one last chart to help you think about this.
The Anatomy Of Your BMR
All over the internet you’ll read that men have more muscle than women, so they have higher BMRs. This is true to an extent, but its not a rigorous way to think about it.
In the chart below I’ve computed some resting energy expenditures for men and woman based on organ tissue mass from a very clever study. It shows a rough breakdown of what makes up basal metabolic rate.
If you look at the chart on the right you’ll see that muscles account for less than a quarter of resting energy use. Together the brain, liver, kidneys and heart actually use much more energy. They are also the major cause of the difference between men and women.
Fascinating chart isn’t it 😉
What about your BEE/BMR?
You can use a calculator to estimate your BMR, but it’s only an educated guess.
The best available equations for resting metabolism are the Mifflin-St Jeor:
Men: REE = 10 x weight (kg) + 6.25 x height (cm) – 5 x age (years) + 5
Women: REE = 10 x weight (kg) + 6.25 x height (cm) – 5 x age (years) – 161
We know from a later study that 70% of estimates using this equation were accurate within ±10%, while the total range was ±20% or so. So it’s a good ballpark figure. Just don’t assume it’s perfect, and remember that it can change over time in response to diet and exercise.
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