Exercising Before Food May Help Control Blood Sugar Levels

It has long since been stated that the time at which you eat and exercise on a regular basis is of immense importance. Breakfast is also highly regarded as the most important meal of the day. While the normal assumption has been so far that exercise is better performed after consumption of food, food acting as a fuel for our bodies and breakfast being the foremost source of fuel, a recent study has found the opposite to be far more effective for staying healthy. 


One Study Among Many

Exercising before food is beneficial to health. blue exercise equipment including exercise ball and dumbells

Numerous studies have looked into the beneficial effects of exercising during periods of fasting. One particular study, dated as far back as 2010, looked into this very concept and successfully discovered the same. The effects of fasted training were found to be more potent than training that occurred after being fed. Facilitating the strength and adaptation of muscles to the training exercises in question increased glucose tolerance in the entire body. Insulin sensitivity was also improved in cases of consumption of high-calorie diets. 

However, the 2010 study was conducted on healthy men, still leaving open a question regarding the effects of fasted training on those that are overweight or suffering from obesity. In fact, most studies in this line specifically studied the effects on lean or healthy persons. The study in question is therefore unique, as it followed the impact of the same on overweight and obese men in particular. 

A Different Approach

Exercising before food is beneficially to health. three men of different size and stature standing in a grassy place

Aware of the results of fasting and feeding prior to exercise training on lean healthy men, this study is acknowledging that the precise physiological effects on people who are overweight or obese could be different on a structural level. Similar studies had been conducted in the past on obese and overweight women, but not on men in that category, keeping in mind that biological sex can also affect physiology. 

Exercising before food is beneficially to health. shirtless overweight man with brown hair and beard sitting on a sofa with a TV remote in his hand

The study published in October 2019, in the Journal of Clinical Endocrinology and Metabolism, was conducted by scientists from the University of Bath and the University of Birmingham, and divided into two sub-groups, acute and training groups.

The acute group was to calculate the results in a preliminary manner, and the results of a single day test of exercise post and prior to eating breakfast for obese men. The training group was designed to check the long term effects of exercise prior to food consumption in obese men. The main purpose of approaching this study from this specific perspective was because of the effect that being sedentary and lethargic can have on muscle movement as well as insulin sensitivity. 


The Acute Study

Exercising before food is beneficially to health. white bowl and plate with milk and cornflakes with dry fruit next to stalks of wheat and grains

The acute group consisted of 12 overweight and obese men from Birmingham who were given a standardized breakfast, usually consisting of cornflakes, skim milk, and toast with spread and jam. 

Their arrival and food consumption in the laboratory was monitored carefully, as was their meal consumption for the 48 hours prior to coming to the lab. This was to ensure that no meals were eaten in excess that could affect the outcome of the testing. 

Exercising before food is beneficially to health. person wearing helmet cycling next to the ocean at sunrise

After breakfast, a 90-minute rest was granted and then 60 minutes of cycling was carried out by the subjects. At each stage, samples of blood, muscle tissue and gas were collected from each subject and tested. 

The same test was also conducted in reverse on the 12 men, with breakfast being consumed immediately after the exercise was completed. It was found in this acute study, that the number of intramuscular lipids (a biochemical found in muscles which helps control insulin levels), was far greater utilized in those who exercised prior to breakfast.



The Training Study

Exercising before food is beneficially to health. overweight man exercising in a gym with a trainer using a silver exercise ball

The second test required 30 male participants from the region of Bath, UK. They were split into 3 groups; Group 1 was the no-exercise group, essentially maintaining the same routine as before.  Group 2 included those who exercised after consumption of breakfast,  and finally Group 3, who were required to exercise prior to breakfast. They were monitored for a period of 6 weeks to mark the results.  

It was first noted that group 3 burned double the amount of fat than the other exercise group. This is because overnight fasting improves insulin sensitivity, and lower insulin levels assist the body drastically in burning fat. While this burning of fat did not have a direct effect on weight loss, it improved the overall health of the participants in a number of ways. The tests revealed an increase in protein buildup in the body as well as a significant strengthening of the muscles. In fact, insulin levels appeared to remain stable for Group 3 even post-consumption of breakfast. 


Effect on Future Studies 

Exercising before food is beneficially to health. doctor in lab coat looking into a microscope

It was conclusively found in this study that exercising during fasting periods, essentially prior to the consumption of any major meal, as opposed to post-consumption (following a set period of rest time), was far more beneficial for the body, especially in the case of obese and overweight men. While the amount of weight lost and the fitness gained by control groups 2 and 3 were relatively the same, there was an increase in glucose-delivering proteins to the muscles that can help improve movement and lethargy.  In other words, exercising before breakfast burned more fat and made the muscles more efficient.

The study focused on the consumption of food high in carbohydrates, so future studies are aimed at looking at the possibilities in relation to low-carb meals, as well as the effects of the above tests on women because the current test was sex-specific. This study has paved the way for much future research into the benefits of fasted exercising, which has been revealed to be a viable method by which both healthy and obese men can improve their health. 

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