The Children of the 90s analysis of 6,291 participants found that genetic factors explain about a quarter of variation in BMI trajectories from ages 1 to 18, and that genes influencing infant size often differ from those affecting teenage size. BMI around age 10 and an individual's overall growth trajectory were more closely linked to later cardiometabolic risk than very early childhood BMI. The results, published in Nature Communications, suggest mid-childhood and sustained growth patterns may be better targets for prevention.
Early High BMI Doesn't Always Predict Lifelong Obesity, Study of 6,291 Children Suggests
Having a high body mass index (BMI) as a young child may not reflect a lifelong risk of obesity, researchers suggest. Sebastian Kahnert/dpa
A new analysis of the long-running Children of the 90s cohort suggests that a high body mass index (BMI) in early childhood does not necessarily indicate a lifelong tendency to obesity. Researchers used growth modelling and genetic data from 6,291 participants to track how body size changed between ages 1 and 18 and to estimate how much of that variation is explained by genetic factors.
The study found that genetics account for roughly one quarter of the differences in childhood BMI trajectories. Importantly, the genes that appear to influence body size in infancy are not always the same as those that matter in adolescence.
“Parents often worry when a child gains weight early or grows differently from others, but our findings suggest that genetic variation can influence these changes,”— Dr Geng Wang, University of Queensland Institute for Molecular Bioscience.
The researchers also identified that BMI measured around age 10, and an individual’s overall growth trajectory from 1 to 18 years, were more strongly associated with markers of later cardiometabolic risk — including diabetes, high cholesterol and heart disease — than BMI measured in very early childhood. That suggests mid-childhood and sustained growth patterns may be more useful targets for predicting and preventing long-term risk.
“We are ignoring important information when assessing growth based on population averages,”— Dr Nicole Warrington, University of Queensland. The study is published in Nature Communications.
Professor Nicholas Timpson, principal investigator for the Children of the 90s study, added that the findings improve understanding of how genetic influences on body size change across the life course and could help refine when and how to intervene to reduce future health risks.
Public-health figures underline the urgency: England's National Child Measurement Programme reported that in 2024/25, 10.5% of Reception pupils and more than a fifth of Year 6 pupils were classified as obese, with boys more likely than girls to be overweight. Excluding the pandemic peak, the Reception obesity rate in 2024/25 is the highest since records began in 2006/07.
What this means: A high BMI in infancy should not be taken as a definitive signal of lifelong obesity. Clinicians and parents may get more predictive information from BMI around age 10 and from tracking a child’s growth pattern over several years. The authors call for further research to pinpoint the best ages and strategies for preventing obesity and associated health problems in later life.
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