People with genetic mutations associated with obesity are now more likely to be heavier than people with the same mutations born before the recent obesity epidemic. Liam Wright of University College London and colleagues report these findings in the June 19 issue of the Journal. PLOS genetics.
Obesity rates among children and adults have risen sharply over the past 50 years. But strangely, rates of extreme obesity are increasing faster than the overall increase in body mass index (BMI), an estimate of body fat based on height and weight. This trend suggests that some people are particularly susceptible to environmental factors that promote weight gain, such as increased availability of processed foods and decreased physical activity. One cause of this susceptibility may be genetics.
To investigate this trend, researchers compared the BMI of people in four UK birth cohorts born before or during the rise in obesity rates and the presence or absence of several genetic variants previously associated with obesity. The study included BMI data from early adolescence to adulthood for individuals born in the UK in 1946, 1958, 1970 and 2001. Their analysis showed that these genetic variations were more strongly associated with having a high BMI in two recent cohorts and became even more pronounced at older ages and among people with a higher BMI. These findings suggest that people with a genetic predisposition to high BMI are likely to be more susceptible than others to environmental changes that promote obesity.
Researchers note that it is unclear why the association between genetics and BMI is stronger in younger cohorts. However, researchers believe that changes in the environment, such as an increase in fast-food restaurants and processed foods, may have increased the expression of genetic mutations that promote increased calorie consumption and, in turn, higher body mass index. They conclude that further research is needed to identify the specific environmental factors responsible for strengthening the relationship between genetics and BMI.
The authors add: ”The obesity epidemic has increased BMI regardless of genotype, but those most affected are those who are genetically predisposed to high BMI.”
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Reference magazines:
Wright, L. Others. (2026) Genetic risk for high body mass index before and during the obesity epidemic: a cross-cohort analysis of four UK birth cohort studies. PLoS Genetics. DOI: 10.1371/journal.pgen.1012138. https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1012138
