- Ghrelin is a hormone in the body that regulates hunger and appetite.
- People with higher levels of ghrelin generally have a harder time losing weight.
- Past studies have shownn that exercise may help subdue ghrelin levels.
- Now, researchers from the University of Virginia report that intensive exercise suppresses ghrelin levels more than moderate exercise.
Ghrelin is a hormone in the body that is responsible for stimulating appetite and making you feel hungry by increasing activity in a specific area of the brain.
People with higher levels of ghrelin generally have a harder time losing weight. Past studies have shown that ghrelin levels may increase when a person is dieting because the body is hardwired to protect itself from starvation.
At the same time, there is evidence to suggest that exercise may help lower ghrelin levels.
Now, researchers from the University of Virginia, in Charlottesville, have found that vigorous exercise suppresses ghrelin release more than
For this study, researchers recruited eight healthy male participants with an average age of 43 and six healthy female participants with an average age of 32.
Their ghrelin levels were tested before they started exercising, after moderate-intensity exercise, and following high-intensity exercise. Participants also self-reported what their appetite was like after each session.
There are two types of ghrelin: acylated (AG) and deacylated (DAG). DAG makes up the bulk of ghrelin in the body, accounting for about 80% of this hormone.
Past research has shown that AG is responsible for controlling hunger and a number of bodily processes, such as energy balance regulation and prompting
DAG was originally considered an inactive form of ghrelin, but now scientists know it is involved in a variety of
“Ghrelin is a hormone released from the stomach, and has been shown to cross the
“Our group had previously completed a meta-analysis on how acute exercise affects ghrelin,” Anderson continued.
“We found that exercise intensity may affect this relationship. In addition, we identified several ‘gaps’ within the literature, including previous studies mainly including males only, and studies only measuring one form of ghrelin. Therefore, this present study sampled all forms of ghrelin in both males and females, while focusing on exercise intensity.”
– Kara Anderson, PhD
At the study’s conclusion, the researchers found that female participants had higher levels of total ghrelin and of the DAG form of ghrelin compared to male participants.
Both gender groups showed reduced DAG ghrelin levels after vigorous exercise, when compared to moderate exercise and control readings.
“Our results confirmed what our meta-analysis suggested: That higher intensity exercise would suppress hunger more than a lower intensity exercise bout,” Anderson said. “Based on what we know about how ghrelin can interact with the ‘hunger center’ of the brain — the hypothalamus — these results were not surprising.”
The scientists further found that only female participants also had significantly reduced AG form of ghrelin after high-intensity exercise.
“This strengthens the need for more work on how biological sex may impact exercise and hormonal responses,” Anderson said. “High-intensity may be superior to moderate-intensity exercise for reducing ghrelin levels and modifying hunger, and sex may impact this response.”
“We will be looking at how exercise intensity and ghrelin levels affect appetite in individuals with obesity and/or prediabetes,” she added. “This will further this research to identify whether fat tissue and/or insulin resistance impact our results.”
MNT also spoke with Mir Ali, MD, a bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA, who was not involved in this research.
Ali told us he found the study’s findings to interesting, but he also highlighted some caveats to keep in mind.
“We all know that there’s beneficial effects from exercise, and the study shows that the intensity of the exercise does make a difference,” he said. “But [there are] some limitations — a very small study, only six patients in one group and eight in the other. And it’s hard to come up with really definitive conclusions with such a small group of patients.”
“It would be helpful to expand it to a larger group of people so they’d be more applicable, and try to quantify how long this effect lasts, and what is the optimal time and number of minutes to do intensive exercise,” Ali continued. “These are things that obviously are going to be different for everybody, but some guidelines would be helpful.”
“Anything besides medications and surgeries that can help patients decrease their appetite is helpful,” he explained. “The problem comes when patients are significantly overweight — it is hard to do intensive exercise and it’s hard to keep it up. You may be able to do it here and there, but doing that on a consistent basis, on essentially a daily basis, to suppress your appetite is tough.”
For those looking for ways to naturally lower their hunger, Ali advised reaching for foods that take more energy to break down, such as proteins and vegetables, as they tend to suppress appetite longer.
“Simple carbohydrates and sugars that are broken down readily tend to suppress the appetite for less period of time, so we emphasize to our patients to reduce carbohydrate and sugar intake so they feel full for longer,” he explained.
