One of the main reasons why people start/continue to workout is to manage their weight, but a new study suggests the intensity and length of workout could derail your fitness goals of losing weight. A study published in the Journal of Endocrinology found that different types of exercise can affect appetite, thus overall caloric consumption.
The study split 16 men into 2 different groups, the first group focused on intensity of running the other focused on length of time running. Throughout the workout and for 3 hours post-workout, scientists drew blood to measure acylated ghrelin levels. Acylated ghrelin is believed to affect hunger in a positive relationship, as acylated ghrelin increases so does hunger. The scientists also measured qualitatively how the men felt by having them rate their hunger levels.
Results showed exercise lowered acylated ghrelin compared to when they remained sedentary. The affects were more definitive when workouts were more intense or lasted longer. The more intense the run or the longer the run showed lower acylated ghrelin compared to slower jogs and shorter runs. For longer runs, acylated ghrelin was still low 90 minutes after the run.
However, the subjects differed on feelings of hunger based on the length and intensity of the run. The subjects who ran longer reportedly felt fuller longer. The subjects participating in the higher intensity runs felt hungrier sooner after the workout even though their acylated ghrelin was still quite low.
The study suggests that if we wish to have our workouts diminish our appetite to lower total caloric intake, we need to increase the intensity and/or length of time working out. Short, low-intensity workouts may not diminish our acylated ghrelin response, thus making us hungrier throughout the day leading to a surplus of caloric intake. The surplus of caloric intake could negatively affect our weight management goals.
Broom, DR., Miyashita, M., Wasse, LK., Pulsford, R., King, JA., Thackray, AE., Stensel, DJ. (2017). Acute effect of exercise intensity and duration on acylated ghrelin and hunger in men. Journal of Endocrinology. Mar;232(3):411-422. doi: 10.1530/JOE-16-0561.
Reynolds, Gretchen (2017, August). Exercise as a Weight-Loss Strategy, D6. Retrieved from https://www.nytimes.com/2017/08/09/well/eat/exercise-as-a-weight-loss-strategy.html