There may be an upside to gaining those extra pounds. According to a new study, fat people are more jolly than their skinny friends - because their genes mean they're less likely to get depressed.

Scientists from McMaster University in Canada found the so called "fat gene" FTO is also a "happy gene".

Fat mass and obesity-associated protein (FTO) is the major genetic contributor to obesity but scientists found that it is also associated with an 8% reduction in the risk of depression.

Results showed those with FTO gene showed significantly less signs of depression.