Exercise does a body good at any time of day, but it might come with extra health benefits before breakfast.
People who worked out on an empty stomach after fasting overnight burned double the amount of fat compared to those who exercised after eating the first meal of the day, in the study published by the Journal of Clinical Endocrinology and Metabolism.
They were also able to better control their blood sugar levels and adjusted easily to their before-breakfast workout sessions.
“We found that the muscles adapted more to exercise and people’s overall response to insulin was improved,” Javier Gonzalez, the study co-author and a senior lecturer in the department for health at the University of Bath, told TODAY.
“For otherwise healthy people, exercising before breakfast poses few issues," he added. "In our study, the participants did not report that the exercise felt any more difficult.”
The study was conducted in the U.K. and included 30 overweight or obese sedentary men split into different groups.
To see how their bodies would respond to a longer-term training regimen while “manipulating nutrient-exercise timing,” 12 participants were randomly assigned to consume a carbohydrate breakfast drink, then engage in a cycling session two hours later.
Nine other participants did the same exercise but on an empty stomach after fasting overnight. They were then given the breakfast drink two hours after their workout.
The men in both groups worked out three times a week for six weeks. They had no other diet controls or restrictions.
The remaining nine participants were assigned to a control group that didn’t do any exercise.
Besides burning double the amount of fat as the group who exercised after breakfast, the before-breakfast exercisers showed muscle adaptations that can be important for controlling blood sugar levels.
“For example, we observed a greater increase in the key sugar transporter known as GLUT4, which helps the muscle take sugar out of the bloodstream,” Gonzalez said.
They burned more fat because their lowered insulin levels meant they could use more of their fat tissue as fuel, the authors stated. But, they didn’t lose more weight than the after-breakfast exercisers, likely because both groups consumed and burned the same amount of calories.
Previous research, which was focused on athletes and lean people, has suggested exercising before breakfast can increase fat use and promote beneficial adaptations in muscle, Gonzalez said. This was the first study to show the same effects in overweight and obese men.
The authors are now “very keen” to find out whether the results could also apply to women, Gonzalez added.
“There are some differences between men and women in their fat-burning during exercise," he said. "This may be important for the response to breakfast and exercise.”
Other experts, including Daniel Pink, author of “When: The Scientific Secrets of Perfect Timing,” have praised morning exercise for different reasons.
You get it over with right away, there’s less chance of something interfering with your workout and you have a momentum, Pink said. It also helps people start the day with a mood boost.
But exercising before breakfast is not for everyone, including those with diabetes who are on insulin treatment and could increase their risk of hypoglycemia, Gonzalez said.
Healthy people who are simply worried they won’t have the energy to get their heart pumping before their morning bagel or scrambled eggs can try drinking some strong black coffee before their workout to help the exercise feel a little easier, he added.