The key variant of the FTO gene is thought to be carried by 63% of people.
The New England Journal of Medicine study, by the University of Dundee, carried out eating tests on 100 children aged four to 10.
Those with the gene variant chose foods with more sugar and fat, suggesting they were instinctively drawn to them rather than healthy options. Each child in the study took part in three eating tests, offering a range of different food types.
The researchers found that the gene variant had no impact on the speed at which the body broke down food, or on how active people were. There was also no evidence that those who carried it had any trouble registering when they were full up and should stop eating. However, they did seem to be instinctively attracted to more calorific foods.
Researchers say that this study shows that the link between obesity and this gene is due to overeating and that a carefully monitored diet could prevent people with the gene from becoming obese.
Research has shown that people carrying one copy of the key FTO variant (49% of the population) have a 30% increased risk of obesity, while for those carrying two copies the increased risk is almost 70%. However, researchers say that it is likely that there are many different genes linked to obesity.
