Certain Genes Predict Abdominal Fat Regain After Weight Loss

Genetic effects on abdominal obesity may be more pronounced than those on general obesity during weight regain, a new study suggests.

People with a genetic predisposition for abdominal adiposity regained more weight around their waist after weight loss than other people.

However, people with a genetic predisposition for a higher body mass index (BMI) did not regain more weight after weight loss than others.

These findings are from a secondary analysis of data from participants in the Look AHEAD trial who had type 2 diabetes and overweight/obesity and had lost at least 3% of their initial weight after 1 year of intensive lifestyle intervention or control, who were followed for another 3 years.

The study showed that change in waist circumference (aka abdominal obesity) is regulated by a separate pathway from overall obesity during weight regain, the researchers report in their paper, published in Diabetes in July.

“These findings are the first of their kind and provide new insights into the mechanisms of weight regain,” they conclude.

“It was already known in the scientific literature that genes that are associated with abdominal fat deposition are different from the ones associated with overall obesity,” Malene Revsbech Christiansen, a PhD student, and Tuomas O. Kilpeläinen, PhD, associate professor, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark, said in a joint email to Medscape.

Genetic variants associated with obesity are expressed in the central nervous system. However, genetic variants associated with waist circumference are expressed in the adipose tissues and might be involved in insulin sensitivity, or fat cell shape and differentiation, influencing how much adipose cells can expand in size or in number.

If those genes can function as targets for therapeutic agents, this might benefit patients who possess the genetic variants that predispose them to a higher waist-to-hip ratio adjusted for BMI (WHR-adjBMI), they said.

“However, this is a preliminary study that discovered an association between genetic variants and abdominal fat changes during weight loss,” Christiansen, and Kilpeläinen cautioned.

Further study is needed, they said, to test the associations in people without obesity and type 2 diabetes and to investigate this research question in people who underwent bariatric surgery or took weight-loss medications, “especially now that Wegovy has increased in popularity.”

“Genetic profiling,” Christiansen and Kilpeläinen noted, “is becoming more popular as the prices go down, and future treatments are moving towards precision medicine, where treatments are tailored towards individuals rather than ‘one size fits all.”‘   

In the future, genetic tests might identify people who are more predisposed to abdominal fat deposition, hence needing more follow-up and help with lifestyle changes.

“For now, it does not seem realistic to test individuals for all these 481 [genetic] variants [predisposing to abdominal adiposity]. Each of these genetic variants predisposes, but is not deterministic, for the outcome, because of their individual small effects on waist circumference.

“It should be stated,” they added, “that changing the diet, physical activity pattern, and behavior are still the main factors when losing weight and maintaining a healthy body.”    

Maintaining Weight Loss Is the Big Challenge

“Lifestyle interventions typically result in an average weight loss of 7%-10 % within 6 months; however, maintaining the weight loss is a significant challenge as participants often regain an average one third of the lost weight within 1 year and 50%-100% within 5 years,” the researchers write.

They aimed to study whether genetic predisposition to general or abdominal obesity predicts weight gain after weight loss, based on data from 822 women and 593 men in the Look AHEAD trial.

On average, at 1 year after the intervention, the participants in the intensive lifestyle group lost 24 lbs (10.9 kg) and 3.55 inches (9 cm) around the waist, and participants in the control group lost 15 lbs (6.8 kg) pounds and 1.98 inches (5 cm) around the waist.

From year 1 to year 2, participants in the intensive lifestyle group regained 6.09 lbs and 0.98 inches around the waist, and participants in the control group lost 1.41 lbs and 0.17 inches around the waist.

From year 1 to year 4, participants in the intensive lifestyle group regained 11.05 lbs and 1.92 inches around the waist, and participants in the control group lost 2.24 lbs and 0.76 inches around the waist.

From genome-wide association studies (GWAS) in about 700,000 mainly White individuals of European origin, the researchers constructed a genetic risk score based on 894 independent single nucleotide polymorphisms (SNPs) associated with high BMI, and another genetic risk score based on 481 SNPs associated with high WHR-adjBMI.

Having a genetic predisposition to higher WHR-adjBMI predicted an increase in abdominal obesity after weight loss, whereas having a genetic predisposition to higher BMI did not predict weight regain.

“These results suggest that genetic effects on abdominal obesity may be more pronounced than those on general obesity during weight regain,” the researchers conclude.

The researchers were supported by grants from the Novo Nordisk Foundation and the Danish Diabetes Academy (funded by the Novo Nordisk Foundation). The authors report no relevant financial relationships.

Diabetes. Published online July 26, 2023. Abstract.

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