Ghrelin
Episodes
Topic Pages
News & Publications
-
Hunger cues are influenced by more than just an empty stomach, with hormones like ghrelin playing powerful roles as appetite regulators. A recent study found that both exercise intensity and sex significantly influence ghrelin levels, markedly influencing appetite.
Researchers measured lactate threshold and peak oxygen consumption in 14 untrained males and females engaging in three different cycling sessions: a control session with no exercise, a moderate-intensity session at lactate threshold, and a high-intensity session at 75% of the difference between lactate threshold and peak oxygen consumption. Then, they assessed the participants' appetite perception.
They found that females had considerably higher total ghrelin and deacylated ghrelin levels at baseline than males. In both groups, high-intensity exercise promoted lower levels of deacylated ghrelin than moderate-intensity and no-exercise sessions. Notably, only females exhibited reduced acylated ghrelin levels during high-intensity exercise. Additionally, hunger scores were higher during moderate-intensity sessions than they were during no exercise.
Ghrelin, often called the “hunger hormone,” is primarily produced in the stomach and stimulates appetite. Deacetylated ghrelin has different effects on appetite regulation than its acylated counterpart.
These findings suggest that high-intensity exercise is more effective than moderate-intensity exercise in lowering ghrelin levels and suppressing hunger, with noticeable differences between sexes in this response. High-intensity exercise also promotes brain health. Learn more in this clip featuring Dr. Martin Gibala.
-
Time-restricted eating may be linked to greater motivation to engage in voluntary exercise. www.sciencedaily.com
Limiting food intake and engaging in exercise are highly effective strategies for weight loss. People who are obese are often sedentary, however, due to physical limitations and a lack of motivation to exercise. Compelling findings from a new study in mice suggest that ghrelin, a hormone linked to appetite, may increase motivation to engage in exercise.
Ghrelin, which is produced primarily in the stomach, stimulates appetite, increases food intake, and promotes fat storage in mice and humans. It is often referred to as the “hunger hormone” and is linked to reward-driven behavior. Previous studies have shown that ghrelin administration increases activity in mice in anticipation of food.
The current study involved mice that were fed on a time-restricted eating schedule (twice daily) versus mice that were allowed to eat freely throughout the day. Both groups of mice ate roughly the same amount of food each day. The mice that were fed on the time-restricted schedule were more motivated to engage in voluntary exercise and ran on an exercise wheel for longer periods. The increase in the animals' activity corresponded to increases in ghrelin levels. Conversely, inhibiting ghrelin attenuated the animals' motivation to exercise.
Hunger-related behaviors such as increased activity are essential to animals in the wild or human hunter-gatherers because they must forage and seek out or hunt for food. Tapping into these ancient hormonally-driven behaviors may help resolve modern-day concerns of obesity and lack of exercise. However, a small study in humans demonstrated that time-restricted eating decreased morning levels of ghrelin (and subsequently appetite), so more studies on the effects of time-restricted eating and ghrelin in humans are needed.