Resting metabolic rate

Written by: Jonine Möller, M.Sc. in Sport Science

Genes play a crucial role in determining our resting metabolic rate (RMR), which is the amount of energy (in the form of calories) we burn at rest to maintain our basic physiological functions. RMR makes up most of the total calories we burn in a day, and variations in RMR can impact our weight gain or loss if we do not eat accordingly.

Studies have shown that genetic variations can account for up to 70% of differences in RMR between individuals. For example, variations in the genes responsible for regulating metabolism, such as the beta-3 adrenergic receptor gene, can affect the efficiency of our metabolism and, therefore, our RMR.

Studies have not been able to prove that resting (or basal) metabolic rate (RMR) determines the likelihood of weight loss or gain.  Thus, people are not overweight due to their metabolism being too slow.  Your metabolism may, however, determine your daily energy needs.  Purely eating more or less or needing more or less food isn’t what ultimately determines whether you pick up weight or not.

If your metabolism is fast, you will just get hungry more quickly after having the same meal as someone with a slow metabolism. Whether you pick up or lose weight remains determined by what you eat. Your body then regulates how much you eat based on your energy needs.  Whether your metabolism is slow or fast, you will pick up weight if you eat too much sugar, refined carbohydrates and processed foods.

The size of one’s body is the greatest determining factor of their RMR. Thus, the most effective way to increase your RMR would be to build muscle mass. For this reason, resistance training increases RMR, whereas endurance training doesn’t have significant effects.

Long-term calorie-restricted diets decrease RMR.  Thus, for weight loss, just eating less is not the answer. A change to a healthy diet is needed. Numerous lifestyle factors and the results of other traits should be considered for prescribing weight loss diets. Consult with a dietitian or nutritionist for help with your individual needs. 

Ageing also significantly decreases RMR unless exercise and diet are sufficient to counter muscle mass loss due to sarcopenia (age-related muscle mass loss).

In conclusion, our genes play a significant role in determining our RMR, which can impact how much and how regularly we need to eat and, in turn, may impact our weight gain or loss. While genetics are a factor, it is essential to maintain a healthy lifestyle to support a healthy metabolism and keep weight in check.

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