Some studiesTrusted Source suggest that the effectiveness of exercise may be tied to when a person eats.
However, it is rarely possible to translate findings from studies in lean people to those with obesity.
So, scientists from the Universities of Bath and Birmingham, both in the United Kingdom, set out to see if meal and exercise timing had a similar link in people with overweight or obesity.
Having obesity and living a relatively sedentary life can lead to an increased risk of cardiovascular disease.
This is because insulin sensitivity is reduced, and hyperinsulinemia — a condition characterized by excess insulin levels — is increased.
Finding a way to prevent these insulin-related effects could potentially prove to be life-saving.
The study, which now appears in the Journal of Clinical Endocrinology and Metabolism, aimed to examine how exercising before and after eating affected muscle fat stores and insulin response. It was the first to look at this relationship in people with overweight or obesity.
The experiment, which lasted for 6 weeks, involved 30 men the researchers categorized as either overweight or obese.
“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,” says Dr. Javier Gonzalez, from the University of Bath’s Department for Health.
Participants who exercised before breakfast burned twice as much fat as those who exercised after eating the same meal.
There is a simple reason for this: When people fast overnight, they have lower insulin levels during exercise, allowing their body to use up more fat.
“Importantly, while this didn’t have any effect on weight loss, it did dramatically improve their overall health,” notes Dr. Gonzalez.
The muscles of those who exercised before breakfast responded better to insulin, better controlling blood sugar levels in the body.
Dr. Gonzalez says that this effect is “all the more remarkable, given that both exercise groups lost a similar amount of weight and both gained a similar amount of fitness.”