Researchers want to test if their findings among mice also apply to people
Restricting how much food is eaten at mealtimes could have the potential to increase the motivation to exercise, a study has suggested.
Researchers in Japan believe this could be the result of a surge in the hormone ghrelin after they observed mice began to exercise voluntarily following a period of fasting.
They said their findings indicated that better diet control, such as limiting food intake or intermittent fasting, could help overweight people maintain a more effective exercise routine and lose weight.
Ghrelin, often referred to as the ‘hunger hormone’, stimulates appetite by increasing the motivation to eat.
The hormone has also been reported to be essential for endurance exercise by increasing metabolism to meet the energy demands of prolonged exercise.
Food and diet
The team, from Kurume University School of Medicine, said that while previous studies have suggested a relationship between ghrelin and exercise, it was not known if the hormone’s levels had a direct effect on motivation.
They decided to investigate the relationship between ghrelin levels and exercise in mice by comparing food intake and activity between those with free access to food and those fed only twice a day for a limited time.
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The researchers found that although both groups ate a similar amount of food, the mice on a restricted diet ran significantly more.
Meanwhile, mice genetically altered to have no ghrelin and on the restricted feeding diet ran less than the mice given free access. However, this could be reversed by administering ghrelin.
The team found that mice given free access to food and also given ghrelin ran significantly more.
More work needed
“Our findings suggest that hunger, which promotes ghrelin production, may also be involved in increasing motivation for voluntary exercise, when feeding is limited,” said researcher Dr Yuji Tajiri.
“Therefore, maintaining a healthy eating routine, with regular mealtimes or fasting, could also encourage motivation for exercise in overweight people.”
However, Dr Tajiri warned that their findings, which have been published in the Journal of Endocrinology, were based on animal studies.
“Much more work is needed to confirm that this ghrelin response is also present in people,” he said.
“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.”
The team now plan to carry out more experiments to confirm their findings in humans.