People who find it easy to lose weight and keep it off may owe their slender physiques to genetic factors rather than lifestyle choices, new research suggests.
More than 60% of adults in the UK are overweight, with the soaring obesity rate attributed to environmental factors such as easy access to high-calorie foods and increasingly sedentary lifestyles.
Yet “some people seem able to eat what they like and remain thin”, notes specialist news site ScienceDaily, which adds: “This has led some people to characterise overweight people as lazy or lacking willpower.”
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Professor Sadaf Farooqi, who led the new research, said: “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 that we might wish to think.”
In the largest study of its kind on the subject, a team from Cambridge University analysed DNA from 1,622 volunteers classed as thin and 1,985 from severely obese volunteers, as well as a control group of 10,433 people of average weight, in order to assess the role that genetics plays in weight loss and gain.
The study, outlined in a paper in journal PLOS Genetics, found that among people with no medical conditions or eating disorders, slim participants had a significant advantage when it comes to staying thin thanks to their genes.
DNA is comprised of a sequence of molecules known as base pairs represented by the letters A, C, G and T, which make up an individual’s genes.
These genes affect how our body functions, and changes in the letters found within the base pairs - for example, a C in place of an A - can have “subtle or sometimes dramatic changes on features such as hair colour and eye colour but also on a person’s weight”, says ScienceDaily.
The researchers identified several common genetic variants already known to play a role in obesity, but also found some new genetic regions involved in severe obesity and some linked to healthy thinness.
The exact functions of the genes that correlate with lower or higher risks of obesity are not clear, but the experts believe they may be related to levels of appetite and interest in food, and how quickly an individual burns calories, says The Times.
“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,” said Dr Ines Barroso from the Wellcome Sanger Institute, which collaborated on the study.
However, Tom Sanders, emeritus professor of nutrition at King’s College London, emphasised that environmental factors still play a large part in determining weight gain or loss, The Guardian reports.
“This is an important and well-conducted study confirming that precocious severe obesity is often genetically determined and showing convincingly that those who are very thin are genetically different from the general population,” Sanders said.
“However, most obesity is acquired in adult life and is linked to the obesogenic environment we live in (a sedentary lifestyle and abundance access to calorie-dense foods).”
