A new study investigates how the timing of meals and exercise can affect obesity, blood sugar levels, and hormones.
There is a lot of debate about what time of the day is best to exercise. Some people enjoy exercise mid-day, some enjoy exercising at night, and some people enjoy exercising first thing in the morning to start the day off right. Those who choose to perform their daily physical activity in the morning decide whether to do it before or after eating breakfast, and there are pros and cons to both.
Individuals who exercise after consuming breakfast might find that they have more energy before and during their workout, as their muscles and brain are supplied with carbohydrates to fuel them. However, new research suggests that exercising before breakfast can be beneficial. A University of Bath and Birmingham study published in the Journal of Clinical Endocrinology and Metabolism examined the effects of the timing of exercise sessions on weight loss and insulin levels.
Two studies were performed to gather the data. The first study, referred to as the Acute study, included 12 sedentary overweight or obese men that did not have hypertension or potential type 2 diabetes. Participants consumed a breakfast containing 25% of their estimated daily calorie requirements, and comprised of 65% calories from carbohydrate, 20% from fat, and 15% from protein. Next, participants cycled for one hour.
The same experiment was performed on a different day with the same group of people, only the exercise session was performed before breakfast. Researchers collected samples of participants’ expired breath after 30 and 60 minutes into the exercise session to determine how much fat was burned to fuel the workout. Blood samples were taken before and after breakfast, as well as immediately before exercise, which was 90 minutes after breakfast was consumed. Blood tests were examined to determine fat and glycogen usage.
The second study, referred to as the Training study, included 30 sedentary overweight or obese men. Nine participants did not exercise, 12 participants exercised after consuming a drink of 20% maltodextrin solution, and nine participants exercised before consuming the drink. Participants did this every day for six weeks, and this study was performed to determine the effects of the timing of exercise long-term.
Exercise before breakfast burns more fat
There was no difference in weight loss between those who exercised before and those who exercised after breakfast. However, the group that exercised before breakfast burned twice as much fat as the other group. This is due to decreased insulin levels during fasted exercise. Moreover, the group that exercised before breakfast responded better to insulin, which can help maintain steady blood sugar levels. This could potentially decrease the risk of type 2 diabetes and cardiovascular disease.
This study suggests that exercising before breakfast may have a positive effect on levels of insulin and blood sugar. More research is needed to determine if this relationship is causal, and also see what effect this has on type 2 diabetes and cardiovascular disease.
Edinburgh, R. M., Bradley, H. E., Robinson, S. L., et al. (2019). Lipid Metabolism links nutrient-exercise timing to insulin sensitivity in men classified as overweight or obese. Journal of Clinical Endocrinology and Metabolism. doi: 10.1210/clinem/dgz104
Increase health benefits of exercise by working out before breakfast — new research. (2019, October 18). Retrieved October 22, 2019, from https://www.eurekalert.org/pub_releases/2019-10/uob-ihb101719.php.
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