The benefits of regular exercise are very well known. Regular exercise increases energy levels, improves cardiovascular health, lowers blood pressure, and helps prevent obesity by increasing energy expenditure. Regular exercise also helps prevent chronic medical conditions such as diabetes, heart disease, and some types of cancers. We have previously discussed the finding that physical fitness in midlife helps prevent the onset of chronic medical diseases in later life. The World Health Organization recommends 150 minutes of moderate intensity physical activity and exercise per week for health adults. This can help burn off hundreds of calories and decrease the risk of obesity and its numerous complications.
Researchers, led by Dr. James LeCheminant from Brigham Young University, have found that morning workouts and exercise can decrease appetite and help control hunger. The results of their study were published online in the journal Medicine & Science in Sports & Exercise. The researchers used a cross over design to study 18 normal weight and 17 obese women using electroencephalogram (EEG) after 45 minutes of moderate intensity exercise and without exercise. The study participants were shown pictures of food and flowers (as a control) to assess food motivation. In addition, weighed food records and physical activity were recorded after the testing. The researchers found that exercise decreased appetite and hunger for both normal weight and obese women and increased daytime physical activity levels.
The authors wrote, “This study showed that a 45-minute bout of exercise, not BMI classification, resulted in a disproportionately lower neural response to pictures of food relative to pictures of flowers immediately following completion of the exercise session (within 1 hour)”.
The authors also wrote, “Importantly, the disproportionately lower food motivation response to exercise compared to non-exercise in the present study was not associated with a difference in total energy or macronutrient intake (regardless of BMI group). Others have similarly reported that acute exercise did not result in a compensatory increase in energy intake. This finding likely indicates that the effect of a morning-time 45 minute bout of exercise on food motivation is either transitory or not strong enough to significantly influence energy intake over the course of the entire day. If transitory, it would be interesting to test how long the effect of exercise on food motivation lasted, the commensurate change in hormones that may affect appetite (and potentially food motivation) such as leptin or ghrelin, and whether or not the energy deficit caused by the exercise or the exercise itself influenced these hormones… ”.
The authors concluded, “In conclusion, this study demonstrated that a morning time bout of exercise is associated with reduced neurologically-determined food motivation and increased total [physical activity] over 24-hours compared to a non-exercise condition”.
This study is interesting as it shows that exercise not only helps control weight by increasing energy expenditure, but it also decreases appetite and hunger immediately afterwards. It will be interesting to determine how long these effects last and whether the intensity of exercise plays a role in the appetite suppressing effects. These results will need to be reproduced on a larger scale, but they help us understand how exercise helps control weight and decreases the risk of obesity.
See the YouTube video with Dr. James LeCheminant below:
Bliss Hanlon et al. “Neural Response to Pictures of Food after Exercise in Normal-Weight and Obese Women” Medicine & Science in Sports & Exercise published online ahead of print September 12, 2012 doi: 10.1249/MSS.0b013e31825cade5