People with a variant of the first common gene linked to obesity on average eat more, according to new research.
Scientists in Aberdeen have found that people who carry a variant of the FTO gene that is linked to increased obesity - called the "at-risk" variant - eat more food than those who do not have the "at-risk" variant.
The researchers examined food intake of 150 people from the North East of Scotland over seven days and took blood samples as well as other measurements which included checks of their physical fitness and how much energy they burned when they were resting.
They found that people with the variant of the FTO gene, on average, ate between 120 and 290 calories per day more than those who did not have the "at-risk" variant. Some examples of calories could be an apple which has between 60 and 80 calories, a chocolate bar which can have around 120 calories or a sandwich which may contain approximately 300 calories.
There was no association between the variants in the FTO gene and energy expenditure or physical fitness. Volunteers were also eating normally - not preferentially consuming any particular food group such as carbohydrates.
Professor John Speakman, an author of the paper and Director of the Institute of Biological and Environmental Sciences at the University of Aberdeen, said: "Our data clearly suggests that people with this variant of the FTO gene may become fatter because they are driven to consume more food.
"Greater consumption of food does not mean that people are being greedy."
The findings are published online in the journal Obesity.