Slim people enjoy a genetic advantage in weight management, study says

25 Jan 2019 --- A slim figure is largely dictated by one’s genetic makeup, according to a new study from the University of Cambridge, published yesterday in PLOS Genetics. The findings of the study showed that slim people have a genetic predisposition to remain thin. On the other hand, obese people have a “higher risk” of gaining weight based on their genes. This is the largest study to date, with a focus on slim subjects, and it remains to be seen what the results may mean for nutrition.

The study was conducted by a team at the Wellcome-MRC Institute of Metabolic Science, University of Cambridge. Led by Professor Sadaf Farooqi, the study was coined Study Into Lean and Thin Subjects (STILTS). They sought to examine why some people remain slim while others do not. Until now, most studies were focused on obese individuals, with some identifying genes that increase chances of being overweight and others that may be responsible for severe obesity. 

“The evidence is clear, 40 percent of our weight is influenced by our genes,” Farooqi tells NutritionInsight.

Farooqi’s team collaborated with Dr. Inês Barroso’s team at the Wellcome Sanger Institute, in comparing DNA samples from 1,600 healthy thin people, with a body mass index (BMI) of less than 18, with those of 2,000 severely obese people (BMI over 30) and 10,400 people of normal weight (BMI of 18 to 25). 

The researchers found that obese people were more likely to have a certain set of genes, while people who were skinny, on the other hand, not only had fewer genes linked to obesity but also had changes in gene regions newly associated with being healthily thin.

“There are certain genes that increase a person’s chances of being thin. Of course, our genes work with our environment, our diet and our level of activity. We tend to think it is only about what we eat and what we do but a big part has to do with our biology,” Farooqi notes.

To determine the impact of these sets of genes, the researchers added the contribution of the genetic variants to calculate a “genetic risk score.” 

“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 stacked against them,” adds Dr. Barroso.

Thin participants had a significantly lower genetic risk score than obese people, which means it is easier to maintain their weight. Three out of four participants (74 percent) had a family history of being thin and healthy which led the researchers to identify new genes and biological mechanisms that aid people in remaining slim.

What it means for personalized nutrition
Despite the evidence, the importance of proper nutrition in maintaining a healthy weight shouldn’t be slighted, according to the researchers. Only 40 percent of our weight is influenced by our genes, which means that the rest is up to lifestyle choices. 

Nonetheless, the study may help in the fight against obesity by narrowing down what sort of choices are best suited for each person, though more research is warranted.

“We don't know yet which gene behavior affects which choice of food. There is data going to be emerging on that front and I suspect there will be groups of people who may respond better to certain diets or certain types of exercise,” Farooqi notes.

“We are now focused on trying to zoom in on the particular genes that allow some people to stay thin. We want to identify those genes and pathways to target those to maybe make medicine that will help heavy people or advise people on the best way to lose weight for them,” she tells NutritionInsight.

Nutrition has a major part to play but hopefully, this paper will make people understand that we need to take genes into account, Farooqi concludes.

Increasing evidence links genes to weight management. According to a recent study from Uppsala University, which measured how fat was distributed in nearly 360,000 voluntary participants, genetic factors highly influence whether your body stores fat around the trunk or in other bodily parts and this effect is more predominant in women than in men.

Innova Market Insights places “Eating for Me” as one of 2019’s top trends and reports that consumers are choosing their fuel more carefully than ever before with foods that are specifically adapted to their needs. Personalized nutrition is on the rise and moving beyond tailored diets. The growing role for nutrigenomics as a science means that ever smaller demographic groups are being targeted, while technologies that include AI and 3D printing make customization ever more prevalent. 

With genes now being a big part of the equation, the need for even more personalization in nutrition is brought to the fore. Advances in technology allow for greater diversification and consumers are adopting nutritional patterns based on health and ethical criteria. The notion of “food that works for me” has only intensified with an increasing array of options and research becoming available.

By Kristiana Lalou