Exercising before breakfast burns twice more fat than after: Study

People can have better control over their blood sugar levels by changing the timing of when they eat and exercise, according to a study which may help plan lifestyle interventions to counter diabetes and reduce body weight.

The researchers, including those from the University of Bath in the UK, said that people who performed exercise before breakfast burned double the amount of fat than those who exercised after the morning meal.

The results of the study, published in the Journal of Clinical Endocrinology & Metabolism, revealed that performing exercise in the overnight-fasted state could increase the health benefits of exercise for individuals, without changing the intensity, duration, or perception of their effort.

The researchers conducted a six-week study involving thirty male participants classified either as obese or overweight, and compared the results from two groups -- those who ate breakfast before exercise, and those who ate after.

The study also involved a control group of participants who made no lifestyle changes, the researchers said.

The increased fat use is due to lower insulin levels during exercise when people have fasted overnight, indicating that they can use more of the fat from their fat tissue and the fat within their muscles as a fuel, the researchers said.

While the six-week study did not lead to any significant weight loss in the participants, the researchers added that it did have "profound and positive" effects on their health since their bodies were better able to respond to insulin, keeping blood sugar levels under control, and potentially lowering the risk of diabetes and heart disease.

"Our results suggest that changing the timing of when you eat in relation to when you exercise can bring about profound and positive changes to your overall health," said co-author of the study Javier Gonzalez of the University of Bath.

Gonzalez said that the group who exercised before breakfast increased their ability to respond to insulin, which he added was more significant as both exercise groups lost similar amount of weight, and gained similar fitness levels.

"The only difference was the timing of the food intake," he said.

According to the researchers, the muscles from those who exercised before breakfast showed more increase in key proteins, specifically those involved in transporting glucose from the bloodstream to the muscles.

However, the researchers noted that the short-term study involved only men, and they look to explore the longer-term effects of this type of exercise, and whether women benefit in the same way as men.