The time of day when you exercise may be as important as the exercise itself, according to new research published in The Journal of Clinical Endocrinology & Metabolism.
It may sound bizarre, but the explanation is simple: after fasting for several hours overnight, insulin levels are lower, which allows the body to consume more fat during exercise.
The study, conducted by an international team coordinated by Javier Gonzalez of the University of Bath, England, looked at 30 men who were obese or otherwise overweight and divided them into three groups. Participants included in the first two followed an identical physical activity program, but did it at different times of the day: either just after getting up or after breakfast; finally, a third group introduced no alterations in their lifestyle.
The results were surprising: those who worked out on an empty stomach burned twice as much fat as those who postponed their workout after breakfast.
“Importantly, Gonzales specified, although the different timing of the workout had no effect on weight loss, there was a noticeable improvement in the overall health of those who exercised before breakfast”: their muscles responded better to insulin, better controlling blood sugar levels. “This effect,” Gonzales said, “seemed even more extraordinary to us precisely because of the fact that both groups who exercised lost a similar amount of weight.
It should be noted that the trial was done on all-male participants; therefore, it will need to be replicated with a similar study to be conducted with women as well, to verify that the result can be generalized. In addition, in this study the breakfast provided-the same for everyone-was carbohydrate-based, and the authors intend to control whether this changes in the case of a low carb meal.
Source:
Edinburgh RM, Bradley HE et al. Lipid metabolism links nutrient-exercise timing to insulin sensitivity in men classified as overweight or obese. J Clin Endocrinol Metab. 2019 Oct 19.
