The rise in the number of overweight children in Western countries may be as much to do with their genes as their diet and exercise levels, according to a study that has identified a handful of genetic mutations linked with childhood obesity.
Scientists have discovered that children with the most severe kinds of obesity are more likely than other children to have one or more of four genetic variations in their DNA, which could influence such things as appetite and food metabolism.
The discovery is part of a wider search for the genes involved in increasing a person's risk of becoming overweight when exposed to an "obesogenic environment" of high-calorie food and inactivity which is known to affect some people more than others. The study looked at 1000 children with the most severe form of early-onset obesity, which is highly likely to result in obesity in adulthood.
Some of the 10-year-olds in the study weighed between 80kg and 100kg.
Some of the genetic variations revealed by the study were rare but others are relatively common, suggesting an interaction between genetics and environment, which could explain why certain children become obese while others do not, even when they share a similar upbringing.
The Cambridge University study, published in the journal Nature Genetics, identified four new genetic variants linked with severe childhood obesity.