Restricting food access in mice increases ghrelin hormone levels, which can also increase motivation to exercise, according to a study published in the Journal of Endocrinology. The study suggests that increases in the appetite-promoting hormone ghrelin after a period of fasting prompted mice to engage in voluntary exercise. These novel findings suggest that better control of diet, such as restricting food intake to meals or intermittent fasting, could help obese people maintain a more effective exercise routine, lose weight, and avoid debilitating complications such as diabetes and heart disease.
Obesity is a costly and growing global health epidemic that requires more effective intervention strategies to avoid serious complications such as heart disease and diabetes. Food restrictions and regular exercise are the two most important cost-effective strategies for preventing and treating obesity. However, the condition is often associated with a sedentary lifestyle and bad eating habits such as snacking and binge eating. Consequently, following a regular exercise schedule can be difficult due to an inability to exercise for long periods of time or a lack of motivation. Ghrelin, often referred to as the “hunger hormone”, stimulates the appetite by acting on the brain’s reward circuitry that increases the motivation to eat. It has also been reported to be essential for endurance training by increasing metabolism to meet the energy needs of prolonged exercise. Although previous studies have suggested a relationship between ghrelin and exercise, it is not known whether ghrelin levels have a direct impact on motivation to exercise.
In this study, Dr. Yuji Tajiri and colleagues from Kurume University Medical School in Japan discussed the relationship between exercise and ghrelin levels in mice. Food intake and wheel walking activity were compared in mice given free access to food and in mice fed only twice daily for a limited time. Although both groups ate a similar amount of food, the restricted mice ran significantly more. Mice that were genetically modified to have no ghrelin and were on the restricted feeding diet walked less than the mice that were given free access. However, this could be reversed by administering ghrelin. In addition, mice given free access to food and ghrelin ran significantly more frequently. These results suggest that ghrelin may play an important role in motivating feeding and exercise in response to restricted eating plans.
Dr. Tajiri comments, “Our results suggest that hunger, which promotes ghrelin production, can also help increase motivation to volunteer when feeding is limited. Therefore, maintaining a healthy eating routine with regular meals or fasting could also help motivate obese people to exercise. “
Dr. However, Tajiri warns. “These results and previous reports are based on animal studies. It takes so much more work to confirm that this ghrelin reaction is also present in humans. If it can be established in clinical practice, not only will it open up new low-cost diet and exercise strategies, but it may also indicate new therapeutic applications for ghrelin-mimicking drugs. “
Dr. Tajiri and his team now plan to conduct further experiments to confirm these results in humans, to characterize how ghrelin works in the brain to create motivation to eat or exercise, and to investigate possible real clinical benefits for treatment and Obesity prevention.
Reference: “Voluntary practice is motivated by ghrelin, possibly in connection with the central reward cycle” by Hiroharu Mifune, Yuji Tajiri, Yusuke Sakai, Yukie Kawahara, Kento Hara, Takahiro Sato, Yoshihiro Nishi, Akinori Nishi, Ryouichi Masuuma, Tatsuyuki Kak Kojima, October 8, 2019, Journal of Endocrinology.
DOI: 10.1530 / JOE-19-0213