Obesity Risk Now Detectable at Age Five: Experts

Hyderabad: Obesity in adulthood can be predicted as early as the age of five, thanks to a groundbreaking international study involving Indian scientists led by Dr Giriraj Ratan Chandak of the CSIR-Centre for Cellular and Molecular Biology (CCMB), Hyderabad. The team has developed a tool that is based on genetic markers found in childhood.

The discovery comes at a critical time, as the World Obesity Federation warns that over half the global population could be overweight or obese by 2035.

The global study involved over 600 researchers from 500 institutions and analysed genetic data from more than five million individuals, including Indians. The data was sourced from the GIANT consortium and DNA testing company 23andMe.

Using this data, the researchers developed a Polygenic Risk Score (PRS)—a genetic test that predicts obesity risk well before lifestyle factors begin to play a significant role. This allows for early interventions such as tailored diet and physical activity, potentially preventing the onset of obesity-related conditions.

India is facing a growing obesity crisis and also sees high rates of diabetes, hypertension and heart disease. The obesity pattern in Indians differs from that of Europeans, with greater fat accumulation in the abdominal region. Dr Chandak’s earlier studies have shown that genetic risks for non-communicable diseases vary between Indians and Europeans.

For the current study, his team analysed genome data from Indian individuals—both diabetic and non-diabetic—tracked for nearly two decades. This helped identify genetic variants linked to obesity and led to the creation of an India-specific PRS, offering insights relevant to the wider South Asian population.

According to the researchers, the PRS is twice as effective as previous models. “The score can identify risk as early as age five — before other factors come into play,” said assistant professor Roelof Smit from the University of Copenhagen, lead author of the study published in Nature Medicine.

The study found that individuals with a high genetic risk tend to respond well to interventions like improved diet and regular exercise, but are more likely to regain weight once such efforts stop.

Notably, the research highlights how genetic predictions are shaped by ancestry. While the PRS showed high accuracy for individuals of European descent, it was less precise for South Asians. Many obesity-linked genes in Europeans do not show the same effect in Indian populations, underscoring the greater impact of environment and lifestyle.

“Like our previous work on height, this study suggests that nutrition and lifestyle may play a bigger role in Indians than genetics alone,” Dr Chandak noted. “Tailored interventions combining targeted nutrition and lifestyle changes may be more effective for Indian populations.”