Genetics may make some people more vulnerable to obesity

People who carry genetic variations associated with obesity may be more likely to gain excess weight today than individuals with the same genetic traits born before the modern obesity epidemic, according to a new study published in PLOS Genetics.

Researchers from University College London examined data from four British birth cohorts born in 1946, 1958, 1970 and 2001. They analysed body mass index (BMI) measurements from adolescence to adulthood alongside genetic variants previously linked to obesity.

Over the past five decades, obesity rates have risen dramatically among both children and adults. Notably, rates of severe obesity have increased faster than average BMI levels, suggesting that some people may be particularly susceptible to environmental factors that promote weight gain.

The study found that obesity-related genetic variants were more strongly associated with higher BMI in the younger cohorts than in those born earlier. The association was especially pronounced among older individuals and those with higher BMI levels.

The findings suggest that people with a genetic predisposition to obesity may be more sensitive to environmental changes that encourage weight gain. Researchers believe that the widespread availability of processed foods, larger portion sizes and increasingly sedentary lifestyles may have amplified the effects of these genetic factors.

While the exact reasons remain unclear, the authors suggest that modern environments may allow obesity-related genes to exert a stronger influence on eating behaviours and calorie consumption than in previous generations.

“The obesity epidemic has increased BMI regardless of genotype, but it is those most genetically predisposed to high BMI who have been most affected,” the researchers noted.