Social changes have led to a stronger link between genetics and obesity in recent decades, according to a study
A team from the UK has analyzed body mass index (BMI) and genetic variants associated with obesity in four generations of Britons born in 1946, 1958, 1970, and 2001—that is, before and after the rise in obesity rates. The results indicate that people with a genetic predisposition to a high BMI are likely more susceptible than others to changes in their environment that promote obesity, such as those that have occurred in recent decades related to ultra-processed food and sedentary lifestyles. In other words, although genetics has not changed, the obesogenic environment has strengthened its association with obesity. The work is published in Plos Genetics.
Ordovás - Genética entorno
José M. Ordovás
Senior scientist and scientific advisor at the Jean Mayer USDA Human Nutrition Research Center on Aging and professor at the Gerald J and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University.
Rather than changing our view of obesity, this study reinforces it. The rise in obesity is not explained by recent genetic changes, but by environmental changes that disproportionately affect those with a greater genetic susceptibility.
Or, to put it another way, I wouldn't call it an unexpected finding, but rather a good confirmation with cohort data. Obesity has increased too rapidly to be attributed solely to genes, but the current environment may be making genetic predisposition more significant.
The clear limitation is that it doesn't identify which specific environmental components are responsible for the increase and for this interaction with genes.
Morales - Genética entorno
Cristóbal Morales
Head of the Metabolic Health, Diabetes and Obesity Unit at Vithas Hospital in Seville and member of the Spanish Society for the Study of Obesity (SEEDO)
The article is a gem; it's truly beautiful and of great interest. We were already familiar with the general idea, but having four generations of Britons genetically studied and shown to have the current environment—the obesogenic society—amplify the expression of these genes that regulate hunger and satiety is significant. This obesity epidemic isn't actually due to a change in genes, but rather it's the change in environment that allows genetic predisposition to manifest itself more strongly.
A possible headline would be that your postal code makes your genetic code express itself much more strongly. If in children born in the post-war period of 1946 the effect of genetics had an impact of 0.46 on body mass index, we now see that this force has doubled in this latest generation. The obesogenic society causes the genes that predispose us to obesity to express themselves more strongly.
There are also three very important points. First, regarding the unequal distribution of risk, we see that the most obese people have a greater expression of these genes. This helps us understand the biological causes that lead people to be overweight or obese.
Second, it raises a public health issue and the obligation to legislate to protect this population, understanding the impact of obesogenic society on gene expression. And third: we need to move towards precision medicine and delve deeper into diagnosis, because today we know that genetic predisposition sometimes accounts for 50-70% of this weight gain. For me, the headline would be that our postal code is amplifying, is winning out over our genetic code.
It's not simply that genetics itself is changing; what's changing is the expression of those genes, which are currently being expressed twice as strongly as in previous generations. We need to understand this; it compels us to act.
In short, the article is truly excellent, and the methodology is quite good. It provides plenty to discuss, generates much debate, and presents an uncomfortable truth that we have an obligation to address as a public health problem.
Wright et al.
- Research article
- Peer reviewed
- Non-randomized
- Observational study
- People
