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 eight per cent reduction in the risk of depression, the Daily Mail reported.
Researchers had been investigating whether there was a link between obesity and depression.
However, when they investigated the genetic and psychiatric status of patients enrolled in the EpiDREAM study, led by the Population Health Research Institute, they found the opposite was true.
The study analysed 17,200 DNA samples from participants in 21 countries.
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Results showed those with the previously identified FTO gene - the fat gene -showed significantly less signs of depression.
The study finding was confirmed by analysing the genetic status of patients in three additional international studies.
"We set out to follow a different path, starting from the hypothesis that both depression and obesity deal with brain activity," Professor David Meyre, of McMaster University in Canada, said.
"We hypothesised that obesity genes may be linked to depression. The difference of eight per cent is modest and it won't make a big difference in the day-to-day care of patients. But, we have discovered a novel molecular basis for depression," Meyre said.
"It is the first evidence that an FTO obesity gene is associated with protection against major depression, independent of its effect on body mass index," Meyre said.