Childhood Genes & Adult Obesity: Breakthrough Polygenic Risk Score

By Stayinghealthy !


Obesity rates continue to climb worldwide—by 2035, over half the global population may be overweight or obese, according to the World Obesity Federation’s Atlas 2023 report.¹ Early intervention is key, yet current prevention and treatment strategies often begin too late. A landmark study published in Nature Medicine introduces a polygenic risk score (PGS) that predicts who will struggle with obesity in adulthood, as early as age five.

Global Obesity Outlook

The World Obesity Atlas 2023 projects that by 2035:

  • 51 % of the world's population will be overweight or obese;
  • Nearly 2 billion people will meet the clinical definition of obesity (BMI ≥ 30 kg/m²);
  • Childhood obesity could more than double, impacting over 380 million children aged 5–19.

These trends underscore the urgent need for tools that identify high-risk individuals before lifestyle and environmental factors fully manifest.

What Is a Polygenic Risk Score?

A Polygenic Risk Score (PGS) aggregates the small effects of thousands of genetic variants across the genome to estimate a person’s inherited predisposition to a trait—here, body mass index (BMI) and obesity. Researchers drew on the largest and most diverse genetic dataset to date, encompassing over 5 million individuals from the GIANT consortium and 23andMe.

By weighting each variant’s contribution, the PGS functions like a personalized genetic “calculator.” In adults of European ancestry, the new multi-ancestry score explains 17.6 % of BMI variation—nearly double previous PGS models.

Study Design & Methods

  1. **Data Collection**: Genetic and phenotypic data from 5.1 million participants (71.1 % European, 14.4 % American, 8.4 % East Asian, 4.6 % African, 1.5 % South Asian ancestry).
  2. **PGS Construction**: Genome-wide association studies (GWAS) identified obesity-associated variants; these were combined into ancestry-specific and multi-ancestry scores.
  3. **Validation Cohorts**: Over 500 000 individuals from UK Biobank and the longitudinal Children of the 90s study were tested for PGS–BMI association from age five through adulthood.
  4. **Comparative Analysis**: The new PGS was benchmarked against prior best-in-class scores, demonstrating twice the predictive power for adult obesity.

Key Findings

  • Early Prediction: Strong PGS–BMI correlation appears by age five and persists into adulthood.
  • Explained Variance: Multi-ancestry PGS accounts for 17.6 % of adult BMI variation in Europeans vs ~8 % in previous models.
  • Response to Intervention: Higher-risk individuals show greater weight loss on lifestyle programs but also faster weight regain post-intervention.
  • Ancestry Gaps: Prediction accuracy is lower in African-ancestry groups, highlighting the need for more diverse GWAS.

Implications for Early Prevention

Identifying high-risk children allows for:

  • Tailored lifestyle interventions (nutrition, physical activity);
  • Frequent monitoring and behavioral support;
  • Policy measures prioritizing resources for vulnerable populations.

Lead author Assistant Professor Roelof Smit notes, “Intervening before other risk factors arise could make a huge impact on public health.”

Limitations & Future Directions

While promising, the PGS has caveats:

  • Ancestral Bias: Underperformance in non-European ancestries demands more inclusive genetic studies.
  • Environment & Behavior: Genetics interact with diet, socioeconomic status, and psychosocial factors—PGS alone cannot determine destiny.
  • Clinical Implementation: Ethical, legal, and social considerations must guide how genetic risk information is used in children.


The new polygenic risk score represents a major advance in predicting adult obesity from early childhood. By leveraging data from over five million genomes, researchers have created a tool twice as powerful as previous methods. Early genetic screening may pave the way for precision prevention—provided ethical frameworks and efforts to diversify genetic research keep pace.