After you exercise, do you feel repulsed by the idea of eating a meal? If so, you're not alone. For many, exercise reduces appetite. Though this is a normal response to hormonal changes in the brain, overtraining and loss of appetite can be problematic.
Exercise temporarily decreases your appetite, but how long you’ll feel the effects varies based on a number of factors such as type of exercise and duration.
How Exercise Affects Appetite
According to a November 2017 meta analysis of multiple studies published in Clinic and Research in Arteriosclerosis, exercise leads to changes in appetite, hunger and energy intake. Exercise decreases ghrelin levels in the brain while also increasing leptin concentration.
Ghrelin is a hormone produced by the stomach. It releases mainly from the stomach, but can also release in small amounts from the brain, pancreas and small intestine. Gherlin serves many functions in the body. One of its main functions is to increase appetite and stimulate the release of growth hormone. It also promotes fat storage.
Leptin is a hormone fat cells secrete to help regulate body weight. It signals to the brain's hypothalamus. Though the hormone doesn't affect food intake from one meal to the next, it does alter food intake and controls calorie burn over the long term. Its effects are more pronounced when you lose weight and leptin levels fall.
When levels fall, it stimulates appetite to increase food intake as a way to ensure we maintain a normal weight. It's why people who are trying to lose weight often struggle getting those last few pounds to melt away.
Exercise Reduces Appetite for Some
A small-scale June 2008 study of 20 women funded by the National Institutes of Health and presented by The Endocrine Society found that exercise only reduced appetite in lean women. For the obese women who participated, there was no reduction in leptin during intense exercise as was seen in the lean participants. The obese women were able to reduce leptin levels with moderate-intensity exercise. The research suggests obesity interferes with leptin's appetite suppressing abilities and the detection of exercise energy expenditure.
According to a September 2016 meta analysis published in Nutrients, exercise suppresses appetite and doesn't stimulate changes in appetite or energy intake hours after exercise. Some less conclusive evidence suggests women, but not men, respond to starting an exercise regimen with changes in hormones that lead to appetite stimulation, but it isn't known if the differences continue over the long term.
Aerobics Gives More Appetite Suppression
A small-scale February 2013 study of 33 men published in Metabolism showed that while aerobic and resistance training decreases fat mass, the rate of perceived fullness was higher after aerobic exercise. Aerobic activities such as running suppresses appetite more than lifting weights or other forms of resistance training.
When trying to lose weight, monitoring your food intake and increasing physical activity are important. However, working out too much can have negative effects on your body. Overtraining and appetite loss is a real issue. Without proper food intake, you could experience lethargy, decreased performance, increased injury potential and more. While it's true exercise reduces appetite, you need to allow your body adequate time to recover between workouts.
- Clinic and Research in Arteriosclerosis: "Review and Analysis of Physical Exercise at Hormonal and Brain Level, and its Influence on Appetite"
- Society for Endocrinology: "Ghrelin"
- Society for Endocrinology: "Leptin"
- The Endocrine Society: "Exercise Reduces Hunger In Lean Women But Not Obese Women"
- Nutrients: "Exercise, Appetite and Weight Control: Are There Differences between Men and Women?"
- Metabolism: "Beneficial Effects of 12 Weeks of Aerobic Compared with Resistance Exercise Training on Perceived Appetite in Previously Sedentary Overweight and Obese Men"