Fitness

‘Exercising before breakfast lets you lose extra weight’, the Daily Mail reports, perhaps prompting readers to drop their sausage sarnies and pop out for a jog.

However, the Mail’s sweeping headline is actually based on a very small study of just 10 overweight men.

In the study, researchers compared the effects of a single session of exercise performed either before or after breakfast, and how this affected the metabolism (the chemical reactions that provide the body with energy) of fats and carbohydrates afterwards. The researchers also carried out a ‘control’ experiment in which the men did no exercise at all. The 10 men each carried out all three of the experiments to see which one caused the greatest breakdown of fat and carbohydrate and the greatest overall energy expenditure.

The researchers found that fat and carbohydrate breakdown (as measured by blood tests) and overall energy expenditure were greater in the exercise-before and exercise-after breakfast conditions when compared to the no exercise condition – which hardly seems surprising. However, they also found that fat breakdown relative to carbohydrate breakdown was greater, and overall energy expenditure was more, when men exercised before breakfast, compared to when they exercised after breakfast.

Although these results sound promising, they should also be viewed with caution due to the extremely small sample size which could mean that the differences are purely down to chance. Also, despite the headlines, the findings tell us nothing about weight loss, which has not been examined – just the metabolism of fat and carbohydrate in the blood.

Importantly, in order to give meaningful results, it will be necessary to study people under normal living conditions – outside of the experimental laboratory setting.