Scientists at the University of Cambridge say they have discovered the secret of why some people are skinny while others gain weight very easily.
The international team says their findings confirm the idea that, for some people, being thin has more to do with inheriting a set of “lucky” genes than with following a perfect diet or lifestyle.
The study was published in the open access scientific journal PLOS Genetics.
In recent decades, several researchers have discovered hundreds of genetic changes that increase the possibility that a person is overweight.
However, much less focus has been placed on studying the genes of people who are thin.
To carry out this research, scientists in the United Kingdom used DNA samples from 1,600 healthy and thin people, who had a body mass index (BMI) of less than 18. They
compared these samples with those of 2,000 people with severe obesity and those of 10,400 people of normal weight.
They also used and analyzed lifestyle questionnaires to rule out, for example, the existence of eating disorders.
The researchers found that people who were obese were more likely to have a set of genes related to being overweight.
The people who were thin not only had less genes related to obesity but also they exhibited changes in the genetic regions recently associated with thinness.
The principal investigator, Professor Sadaf Farooqi, of the University of Cambridge, asked people to be less prejudiced about the weight of others.
“This research shows for the first time that thin and healthy people are generally skinny because they have a lower load of genes that increase the chances of being overweight and not because they are morally superior, as some people suggest,” he said.
“It’s easy to rush to judge and criticize people for their weight.”
“We have much less control over our weight than we would like to believe.”
Scientists say that the next step is to identify the exact genes involved in healthy thinness.
Your longer-term goal is to see if this new knowledge can help you shape new strategies to lose weight.
Tom Sanders, professor emeritus of nutrition and dietetics at King’s College London, said of the research: “This is an important and well-conducted study that confirms that early severe obesity is often genetically determined.”
He added that he also “convincingly shows that those who are very thin are genetically different from the general population.”
However, he clarified: “The majority of obesity is acquired in adult life and is related to the obesogenic environment in which we live: a sedentary lifestyle and an abundant access to calorie-dense foods.”
Scientists warn that, beyond genes, “most of obesity is acquired in adult life” and has to do with a sedentary lifestyle and a diet too high in calories. Istock.
Professor Tim Spector, also of King’s College London, noted that, despite this, about one third of people in most countries managed to stay slim.
“Part of this is due to genes, but other factors, such as individual differences in lifestyle or intestinal microbes, are probably also responsible,” he said.
Health experts note that, in any case, regardless of the size of your body or your genetic makeup, the old advice to follow a good diet and make a healthy amount of exercise is still recommended.