Understanding the energy balance, or why do we gain weight ?


Food provides energy that we commonly know as calories. The amount of energy needed varies depending on each person but also on each person’s day. Let’s see how that energy works and affects our weight.

The amount of energy needed everyday depends on the individual’s basal metabolic rate and exercise levels. Basal metabolic rate is defined by the energy needed for the body’s vital functions such as breathing, cardiac activity and blood flow. It varies depending on the sex, age, height, weight of the individual. Exercise level differs depending on the individual’s physical activity throughout the day (walking, sitting, working out, running, etc…)

Two other factors come into play in the evaluation of the daily energy consumption : thermoregulation (energy needed to maintain a body temperature of 37°C regardless of the outside temperature) and specific dynamic action of food meaning the energy needed to digest the foods ingested.

A man of average height and weight consumes 2700 kcal per day whereas a woman consumes 2200 kcal on average.

If the calorie intake is higher than the energy consumed, the individual will gain weight. On contrary, if the daily energy consumption is higher than the daily calorie intake, the individual will lose weight.

But where does that energy come from ?

Macronutrients in food we eat provide energy.
One gram of carbs provides 4kcal and so does one gram of protein but one gram of fat provides 9kcal.
Furthermore, one gram of ethanol grants 7kcal, alcohol consumption should hence be limited.

Calorie intake isn’t everything though, in order for the body to function effectively, it needs quality nutrients.

Written by : Alex Zhang, student in nutrition

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