Scientists find why we just can't say no to sex

Researchers at Dartmouth College, found activity levels in a part of the brain known as the the nucleus accumbens allowed them to accurately predict people's eating and sexual behaviour, a major newspaper reported.

Women volunteers were shown pictures of food as well as erotic images and landscapes while their brains were scanned using MRI imaging to monitor their reactions.

The 48 women, who had no idea what the study was about, returned six months later and were weighed and asked to fill out a questionnaire.

Subjects whose brains reacted strongly to the food pictures were found to have gained more weight while those who reacted to sexual images were more likely to have had sex and report stronger sexual urges.

Bill Kelley, associate professor of Dartmouth's department of psychological and brain sciences, says the study demonstrated that the stronger the response to a stimulus, the less able the subject is to say 'no'.

Kathryn Demos, who led the study believes the way different women reacted to the stimulus was a combination of nurture and nature.

She said the idea that all people are equally capable of self-control is naïve and claims the brain's reward centre 'is a very powerful system'.