Researchers from University College London and the Institute of Psychiatry, King's College London found that the FTO gene linked to obesity makes the children carrying it less likely to tell when they are full.
The researchers studied over 3,000 children to see whether the FTO gene has any impact on the ability to burn calories or appetite. What they found is that children with copies of the gene's risky variant were less likely to have their appetite "switched off" when they should be feeling full.

Adult studies have shown that those with two copies of the higher risk version of the gene were on average 3kg (6lb 10oz) and those with a single copy 1.5kg heavier in comparison to those without the gene.

To learn more about the way the gene works, the researchers tested whether children with the higher risk gene variation, aged 8 to 11, had an altered appetite through height, weight and waist circumference measurements, and gave a questionnaire to the parents to learn more about the child's eating habits. What they found was that the children with the higher risk version of the gene tended to overeat and had problems recognizing when they were full. The effects of the gene on appetite was not dependant on age, sex, socio-economic background and body mass index.

Not all people who carry the risky variant of this gene will automatically become overweight, but one thing is certain - they are more susceptible to overeating, which is one of the risk factors for obesity.

The study authors say that the effect of the gene in isolation is relatively small and that it is just a thousand-piece of a jigsaw. Scientists believe that this gene is just one of the many affecting appetite and obesity, each making a small contribution, but together creating a substantial effect.
They believe that this finding is a step in the right direction but the cure for obesity is still far away.