Obesity is a major public health threat. While recent changes in the patterns of obesity in the population are certainly driven by environmental changes, the heritability of obesity is extremely strong. 

Researchers at Boston Children´s Hospital and the University of Cambridge have identified a genetic cause of severe obesity that, though rare, raises new questions about weight gain and energy use in the general obese population.

The research, published in the journal Science on July 19, involved genetic surveys of several groups of obese humans and experiments in mice.

According to the study published yesterday if a specific gene – codenamed MRAP2 – is missing then people will burn less calories.

The study was initially carried out on mice, which were genetically modified to remove the gene, and found they gained significant amounts of weight despite eating the same diet as normal-sized mice.

Researchers have now confirmed that the vital protein is also missing in around 1 per cent of obese humans, suggesting that hundreds of thousands of people could be fatter than normal because of the genetic quirk.

Experts believe that by identifying another ‘defective’ gene they have taken a step closer to developing anti-obesity medication.

The latest research is part of an ongoing quest by scientists to find out whether some people’s genes make them obese.

Previous research from Cambridge has shown that mutation in the genes directly controlling appetite and calorie-burning can cause obesity from childhood.

Reserachers now look forward to expanding the scope of the research, studying additional populations of obese people, including measures of their activity and diet, as well as further exploring how the gene alters energy balance.