‘Genetic dice loaded against them’: Fat people rolled poor genes, concludes largest-ever study

Body weight is “largely influenced” by genes, according to the largest-ever study of its kind. Researchers concluded that slim people won the genetic lottery, while obese people have the deck stacked against them from birth.

The study by Cambridge University aimed to determine why some people manage to stay thin with little effort, while others gain weight easily despite similar lifestyles.

While there are several environmental factors that contribute to the rise in obesity in recent years – such as a high-calorie diet and lack of exercise – the team found there is still a significant variation in weight within a population that shares the same environment.

Previous studies of twins have found that their differing body weight was largely influenced by their genes. It’s also been previously determined that genes can increase a person’s chance of being overweight, and in some people increases their chances of being obese from a young age.

However the vast majority of studies have focused on overweight people. To balance the scales, the team recruited 2,000 ‘thin’ people with a Body Mass Index (BMI) of less than 18kg/m2 that had no medical conditions or eating disorders.

Participants gave saliva samples to enable DNA analysis and answered questions about their general health and lifestyle, in what is thought to be the only study of its kind in the world.

The team then compared their findings with the DNA of 14,000 other volunteers, including 1,985 severly obese people and a further 10,433 people with a normal weight, and shared their results in a study published Thursday in the journal PLOS Genetics.

Results showed several common genetic variants that are already known to play a role in obesity. In addition, the team found new genetic regions linked to severe obesity and healthy thinness. To determine a person’s genetic risk score, researchers then added up the different genetic variants and found the results corresponded with their weight today.

“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,” said Dr Inês Barroso’s of the Wellcome Sanger Institute.

For the first time the research shows that healthy people have a much lower genetic risk score, and fewer genetic variants that increase a person’s chances of being overweight. The researchers say the results are important to understand obesity and counteract the characteristics often attached to overweight people, such as being lazy or lacking willpower.

“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,” explained Professor Sadaf Farooqi, who led the team.

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