Scientists claim to have identified the hormone ghrelin which causes food to appear more appealing.
Pictures of food were shown to 20 volunteers. Twelve viewed the pictures before and after infusions of ghrelin which had a bigger effect on their brains. Scans showed that ghrelin boosted activity of the brain's “reward centres” which fuel desire. Eight others looked at the same pictures without receiving ghrelin.
Ghrelin levels in the gut are known to rise before a meal and fall afterwards, suggesting that the hormone causes hunger and encourages eating.
“This is interesting but it is a very small study. People who are overweight or obese are at increased risk of developing Type 2 diabetes, which can lead to heart disease, blindness and kidney failure", said Jemma Edwards, Care Advisor at Diabetes UK.
"Research which could improve our understanding of what affects people's appetites could potentially help us reduce the number of people developing Type 2 diabetes.
"Currently, 300 people are diagnosed with the condition every day. There needs to be further research into this subject and we'll be following it with great interest."
The findings are published in the journal Cell Metabolism.