Explainer: How genetics shapes obesity and why environment still matters

For many years, obesity was often viewed as a simple result of poor diet or lack of exercise. However, a recent study published in the scientific journal PLOS Medicine shows that the causes of obesity are far more complex. A person’s genes can influence how easily they gain weight, how their body stores fat, how hungry they feel, and how their metabolism works. Researchers identified more than 3,000 genetic variations linked to obesity risk and estimated that inherited factors explain a large proportion of the relationship between parents’ and children’s body mass index (BMI). These variations do not act like a single “obesity gene”. Instead, thousands of small genetic differences work together to influence a person’s chances of gaining excess weight. The researchers emphasised that genes do not determine a person’s future on their own.