BMR and Daily Calorie Needs Formulas

Definition of Metabolic Rate. A measurement of the number of calories needed to perform your body's most basic (basal) functions, like breathing, circulation and cell production. BMR is most accurately measured in a lab setting under very restrictive conditions.

How to Determining Daily Calorie Needs

Estimating daily calorie requirements can be very challenging. Even the very best calculators cannot determine an accurate metabolic rate for every individual because quite simply everyone is everyone is different! However, the formulas established by peer-review medical journals are helpful for the majority of individuals. Those who engage in very high levels of physical activity tend to find the calculator estimations to be too low.

Estimating BMR

Calorie calculators will first estimate Basal Metabolic Rate (BMR). This is effectively the amount of energy expended per day.

BMR is a measure of only the most basic functions (effectively the same as if you rested in bed the whole day). Other terms synonymous with BMR are Resting Metabolic Rate (RMR) and Resting Energy Expenditure (REE). Once BMR has been estimated, various “activity” factors are applied. Once again these are best guesses based on contemporary research. One individual may burn 100 calories on a 10 minute run – another individual may burn 110 calories. Below are two formulas you can use to calculate your BMR.


Calories for Weight Loss

After calculating the BMR, exercise is factored in. Depending on the exercise level chosen, the BMR will be multiplied by anything from 1.2 to 1.9. This provides us with maintenance calories – the amount of calories you could consume each day and neither lose or gain weight.













To get the fat loss figure – 20% of calories is subtracted. The extreme fat loss figure has 40% subtracted. However – there is a “rock bottom” figure that equates to 8 calories per pound of body weight – the extreme fat loss will never be less than this amount. This has been put into the calculator as a failsafe to prevent users from embarking on highly-restricted diets. Such diets need medical care, advice, and monitoring.

It is also not advised to drastically reduce calories, but rather do so gradually or by a maximum of 500 calories per day.

Burning more calories than you eat is what will create a calorie deficit. A calorie deficit of 500 should result in a 1 pound of weight loss a week due to the fact that a pound of fat is made up of 3500 calories(7 days at a 500 deficit = 3500 calories). A 1000 calories per day deficit should result in a 2 pound weight loss per week, although this is a more aggressive approach and it is recommended to start with a lower deficit and build up gradually.

How to Change Your Basal Metabolic Rate

A combination of factors determines your basal metabolic rate such as genetic factors, age, gender and body composition. There's not much you can do to control genetics, age or gender. But you can change your body composition to boost metabolism.

So how do you change your BMR? By Building muscle! When your body is at rest, lean muscle mass will burn more calories than fat.

Several studies have shown that, even after just a few weeks of resistance training, you may be able to see a 7-8% increase in your resting metabolic rate.