We’ve been told of the gene IRS1 which can keep some fortunate people thin however recent research has shown this gene is also linked to conditions usually associated with the obese. Professor Douglas Kiel, from Harvard Medical School in Boston, USA admitted “We were very intrigued by the unexpected finding.” He further explained “People, particularly men, with a specific form of the gene are both more likely to have lower percent body fat, but also to develop heart disease and type 2 diabetes. In simple terms, it is not only overweight individuals who can be predisposed for these metabolic diseases."
British scientists at the Medical Research Council's Epidemiology Unit in Cambridge worked with American scientists on the study which discovered the IRS1 gene seems to be responsible for determining where the fat is stored within the body. Fat stored under the skin presents itself however fat stored around the organs, known as ‘visceral’ tissue cannot be seen so while individuals with the gene appear to be at a weight that is categorised as being ‘healthy’, they are in fact more vulnerable to some fatal conditions. Dr Ruth Loos, the lead British scientist on the study said "What we’ve discovered is that certain genetic variants keep you lean by reducing how much fat you store under your skin. We don’t know for sure, but we can speculate that these individuals are then more predisposed to store fat elsewhere, such as in the liver and in muscles."
The genetic code of over 75,000 people was analysed for the study with the aim of looking for genes which help determine body fat percentage. Professor Jeremy Pearson, associate medical director at the British Heart Foundation, said: "These results reinforce the idea that it is not just how fat you are, but where you lay down fat that's particularly important for heart risk. Fat stored internally is worse for you than fat stored under the skin. "The results help us to understand why some slim people become insulin resistant, which is the first stage of type 2 diabetes, and may lead to better targeted use of medicines to prevent insulin resistance in future. However [the findings] don’t detract from the fact that being overweight is bad for your heart health, so we should still try to stay lean and fit."
Dr Iain Frame, director of research at the charity Diabetes UK, said "This is a robust study, which with further investigation could shed light on why 20 per cent of people with type 2 diabetes have the condition despite being a healthy weight. It is also a clear message that people who appear slim shouldn't be complacent about their health. Eating well and being more active are the most effective ways of reducing the risk of developing type 2 diabetes."