The genetic dice are loaded in favour of thin people and against those at the obese end of the spectrum according to researchers.
Scientists from Cambridge University have found that slim people have a genetic advantage when it comes to maintaining their weight
The researchers looked into why it is well known that changes in our environment, such as easy access to high calorie foods and sedentary lifestyles, have driven the rise in obesity in recent years, there is considerable individual variation in weight within a population that shares the same environment.
Some people seem able to eat what they like and remain thin. This has led some people to characterise overweight people as lazy or lacking willpower.
To date studies have overwhelmingly focused on people who are overweight. Hundreds of genes have been found that increase the chance of a person being overweight and in some people faulty genes can cause severe obesity from a young age.
In the study the team were able to recruit 2,000 people who were thin (defined as a body mass index (BMI) of less than 18 kg/m2) but healthy, with no medical conditions or eating disorders.
They worked with general practices across the UK, taking saliva samples to enable DNA analysis and asking participants to answer questions about their general health and lifestyles.
“As anticipated, we found that obese people had a higher genetic risk score than normal weight people, which contributes to their risk of being overweight. The genetic dice are loaded against them,” explains Dr Barroso who led the research
Importantly, the team also showed that thin people, had a much lower genetic risk score – they had fewer genetic variants that we know increase a person’s chances of being overweight.
“This research shows for the first time that healthy thin people are generally thin because they have a lower burden of genes that increase a person’s chances of being overweight and not because they are morally superior, as some people like to suggest,” says Professor Farooqi. “It’s easy to rush to judgement and criticise people for their weight, but the science shows that things are far more complex. We have far less control over our weight than we might wish to think.”
Three out of four people (74%) in the STILTS cohort had a family history of being thin and healthy and the team found some genetic changes that were significantly more common in thin people, which they say may allow them to pinpoint new genes and biological mechanisms that help people stay thin.
“We already know that people can be thin for different reasons” says Professor Farooqi. “Some people are just not that interested in food whereas others can eat what they like, but never put on weight. If we can find the genes that prevent them from putting on weight, we may be able to target those genes to find new weight loss strategies and help people who do not have this advantage.”