Research has suggested that limiting access to food might increase motivation to exercise.

According to a study by the Kurume University School of Medicine in Japan – published in the Journal of Endocrinology – restricting access to food in mice increases levels of the appetite-promoting hormone ghrelin.

The surge in levels of ghrelin, after a period of fasting, prompted mice to initiate voluntary exercise.

The findings indicate that better diet control – for example limiting food intake to mealtimes or fasting intermittently – could help overweight people maintain a more effective exercise routine.

Ghrelin, often referred to as the 'hunger hormone', stimulates appetite through actions on the brain reward circuitry that increases the motivation to eat.

It has also been reported to be essential for endurance exercise by increasing metabolism to meet the energy demands of prolonged exercise.

Although previous studies have suggested a relationship between ghrelin and exercise, it is not known whether ghrelin levels have a direct effect on motivation to exercise.

Dr Yuji Tajiri, who led the study, said: "Our findings suggest that hunger, which promotes ghrelin production, may also be involved in increasing motivation for voluntary exercise when feeding is limited.

"Therefore, maintaining a healthy eating routine, with regular mealtimes or fasting, could also encourage motivation for exercise in overweight people.

"These findings and previous reports are based on animal studies, however, so obviously much more work is needed to confirm that this ghrelin response is also present in people.

"If it can be established in clinical practice, it not only opens up new cost-effective diet and exercise strategies but may also indicate a new therapeutic application for ghrelin-mimicking drugs."