Exercising on an empty stomach burns 70% more fat, study finds

According to one study, exercising on an empty stomach helps people burn about 70% more fat than those who exercise two hours after eating.

Sports scientists at Nottingham Trent University also found that participants who exercised both fasted and fed in the evening did not overcompensate for calories skipped earlier in the day.

While studies have suggested the benefits of exercise may be increased when done in the morning after an overnight fast, the team’s own research found that evening exercise, between 4 p.m. and 8 p.m. h, is the most popular time for people due to other commitments.

Therefore, the researchers designed the study so that participants would cycle on an exercise bike at 6:30 p.m. at moderate intensity for 30 minutes, before completing a time trial to cycle that far. they could in 15 minutes.

Participants did this twice on different days, once after fasting for seven hours and once after eating a meal two hours earlier. The researchers also measured how much food the participants ate at dinner after exercise.

The results showed that, similar to exercise after an overnight fast, exercising in an evening fast increased the amount of fat burned during exercise.

The amount of fat burned during the 30 minute cycle increased by approximately 70% from 4.5g to 7.7g.

And, while calorie intake at dinner was about 100 kcal higher for those who exercised on an empty stomach, all-day calorie intake was on average 440 kcal lower, when exercise was performed. with an empty stomach.

The researchers also found, however, that despite these benefits, participants covered slightly less distance during the 15-minute time trial, were less motivated to exercise, and enjoyed the exercise less when finished. .

“We wanted to explore the impact of fasting exercise in the early evening, which we believe was the most popular time to exercise during the week,” said sports science researcher Tommy Slater. at the School of Science and Technology at Nottingham Trent University. .

“Fasting before evening exercise may benefit certain health factors by increasing the amount of fat burned during exercise or reducing the number of calories consumed during the day. If practiced regularly, it may improve how the body handles blood sugar spikes after eating.

“However, despite these benefits, daytime fasting appears to reduce people’s physical performance, motivation, and enjoyment, which may make it harder for some people to stick with it over the long term.

Dr David Clayton, an expert in nutrition and exercise physiology at Nottingham Trent University, said: “Combining exercise and fasting can be a powerful way to increase the benefits of exercise, we so would like to evaluate this over a longer period of time and explore other ways to make fasting easier and more convenient for people.”

The study, which included Manchester Metropolitan University and Loughborough University, is reported in the International Journal of Sports Nutrition and Exercise Metabolism.