A new study has found the structure of your grey matter can determine whether you stick to a diet.
Brain scans showed that some people have stronger signals coming from the region of the brain that plays a role in self-control.
Until now, most evidence has suggested that an imbalance in hormones that increase the desire to eat causes people to fall off the weight-loss wagon.
But a team from McGill University, in Montreal, Canada, says their findings add another layer: that activity in the brain's "control" region overrides these hormones - but they insist there are therapeutic techniques to help people with weaker control become successful dieters.
For the study, the researchers recruited 24 participants and studied them at a weight-loss clinic for three months.
They were shown pictures of both appetising foods and scenery while researchers studied the brain activity as they viewed. When the subjects looked at pictures of food, the region of the brain linked to desire became more active.
"We found that the control of body weight is dependent largely on the areas of the brain involved in self-control and self-regulation,' said Dr Alain Dagher, a professor of psychology at McGill University.
In good news for dieters, he added that there were ways to change brain structure such as cognitive behavioral therapy.