Why early weight gain does not always mean lifelong obesity risk

A recent genetic study has found that nearly a quarter of how a child’s body mass index, or BMI, changes over time may be influenced by common genetic variants. More importantly, it suggests that a child’s pattern of growth across the years may reveal more about future health risk than a single BMI reading taken at one age.

The study, published in Nature Communications, analysed 65,930 BMI measurements from 6,291 children in the UK and tracked how BMI changed from age one to 18. (BMI, or body mass index, is a simple measure that compares a person’s weight to their height to estimate whether their body size falls within a healthy range).
Most earlier studies on childhood BMI looked at one age at a time. This one modelled BMI as a trajectory, or a changing curve across childhood and adolescence.

In effect, the researchers were not just asking how heavy a child was at one moment, but how that child’s body size rose, fell or stabilised over time. They say that matters because snapshot studies can miss important individual differences in growth.