Calculating your daily energy requirements

Nov 14, 2011, 3:06 GMT

Cologne - Diet guides and sport magazines often mention the basal metabolic rate (BMR). The human body needs energy even when completely at rest - simply to breathe, for example - said Ingo Froboese, a professor at the Health Centre of the German Sport University in Cologne.

The daily amount of energy expended by the body at rest is the BMR.

The body gets the energy it needs from food, and the BMR depends on various factors such as gender, age and physical condition.

'Additional energy expended during exercise or physical labour is called the physical activity level (PAL),' said Froboese. A small proportion of the body's energy requirements is for thermogenesis, or heat production, which also plays a role in digesting food and increasing heart rate, for example during stress.

According to Froboese, the rule of thumb for calculating a woman's BMR is as follows: 1 kilocalorie (kcal) per kilogram (kg) of body weight multiplied by 24 hours equals daily energy expenditure.

So a woman who weighs 65 kg has a BMR of 1,560 kcal (65 kg x 24 hours). This is how many calories she can consume daily without gaining weight and not exercising.

Men have a BMR of about 1,800 kcal on average. For them the formula is: 1.1 kcal per kg of body weight times 24 hours.

People who find these formulas too imprecise can have their BMR calculated with the help of spirometry, which measures lung function. The procedure is offered by fitness studios and sports physicians.