What Are Basal & Resting Metabolic Rates (RMR)?
These two terms are used interchangeably, although they are not technically
the same. Resting metabolic rate is really what most lay people mean when
they say basal metabolic rate, and I talk here only about resting metabolic
rate (RMR). Basal metabolic rate is a precise calculation with a precise
definition; RMR is close enough for practical purposes.
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| Your metabolic rate = your resting metabolic rate
(easy to calculate reasonably accurately) + energy consumed by your
daily activities (must guestimate). |
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Resting metabolic rate is the energy required by an animal to stay alive
with no activity. Therefore, your real metabolic rate is always significantly
higher than your RMR. Calculating RMR is a very useful first step in calculating
your real metabolic rate.
Your Resting Metabolic Rate (RMR) is one of the main contributing components of energy expenditure (around 70%).
What Determines Resting Metabolic Rate?
A very small number of people have physical conditions that give them strange
resting metabolic rates.
However, for the vast majority of people, resting metabolic rate can be
calculated knowing a few key variables. They are age, sex, weight, height
and fat-free body mass. Fat-free mass is a very important variable. Weight
and height are used in one formula to determine body surface area.
Things That Affect Your Metabolic Rate:
- Muscle - More muscle increases your
RMR.
- Age - Your RMR decreases with age.
- Genetics - A decrease in your RMR can be due to
genetics.
- The Weather - Living in a cold
enviroment can increase your RMR. I
know this sounds strange but you
expend more energy while moving
around in cold weather. It's a alot
easier to move around in summer but
more of an effort to "get going" in
winter.
- Meals - Small regular meals will increase your
RMR.
- Pregnancy - It can increase your RMR.
- Crash Dieting - It will decrease your RMR.
- Supplements - Some supplements can raise your RMR.
When Does The Body Change Resting Metabolic Rate? & Does Cutting Your Food Intake Reduce Resting Metabolic Rate?
The body CAN NOT change resting metabolic rate per unit of fat-free body
mass. Studies have shown this.
Your resting metabolic rate will decrease as you lose muscle. Losing
fat alone will not lower your RMR (and note that you will need to follow
a very sensible program to lose fat without losing muscle). You have probably
heard that people who go on crash diets end up lowering their metabolic
rate, which means when they go off the diet, they put on fat more easily
than before they started. This is because they have lost muscle, they have lowered
their metabolic rate.
However, the amount of energy burnt per unit of
fat-free weight does not change; poor dieters end up with fewer units
of fat-free weight, and that's where their vicious cycle comes from.
Are Some People's Digestive Systems More Efficient Than Others?
No. And your system does not become more or less efficient in response to
changing food intake. Even obese people rarely have more efficient bodies. Researchers inspect
the energy value of feces to determine this.
Given The Same Values For The Variables, How Much Does Resting Metabolic Rate Vary Between People?
In other words, what is the error in the formulas used to calculate RMR?
The latest research indicates there is a low variance in RESTING metabolic
rate [(RMR)] between individuals who have the same values for the key variables.
That is, given someone's age, their fat free mass, their height and their
sex, the formulas are accurate.
"Recent evidence thus supports the conclusion that within-subject variations
in BMR [more or less the same as RMR] are small and insignificant, even
when energy intake and physical activity are uncontrolled, (Shetty &
Soares, 1988). This effectively refutes the Sukhatme-Margen hypothesis."
View All Calculators!
Tris Mardiastuty
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