A new study out of Denmark has shed fresh light on a question that has lingered for years—do girls who reach puberty early face a higher risk of becoming overweight as they grow older?
The answer, it turns out, is yes. And not just for those who struggled with their weight as children. Even girls who started out at a healthy weight but entered puberty earlier than their peers were found to have a higher body mass index (BMI) into their late teens and young adulthood.
This revelation emerges from research conducted by a team at Aarhus University, published in the prestigious American Journal of Epidemiology. Drawing on a substantial cohort of nearly 13,000 Danish children and analysing more than 136,000 height and weight measurements collected over a span of years, the study offers a rare and detailed glimpse into how puberty’s timing influences long-term weight status. The project, known as “Better Health in Generations,” tracked children closely from ages seven to eighteen, far surpassing the scope of previous studies in both size and depth.
Why does this matter? Trends in childhood obesity are rising globally including Malaysia, and scientists have long sought to understand how early life events shape risk later in life. Puberty, marked by rapid physical and hormonal changes, is a crucial window. Timing of its onset varies widely among individuals. While some children mature later, others experience these transitions much earlier—sometimes years before their classmates.
The findings are particularly striking for girls. According to the research, girls who began puberty earlier than average consistently showed higher BMI readings before, during, and after puberty. This pattern persisted even when accounting for those who were not overweight in childhood. In other words, early-maturing girls seem to be uniquely vulnerable to gaining more weight as they approach adulthood.
The study’s comprehensive approach sets it apart. Previous research often relied on just one measurement of BMI and a single milestone, such as age at first menstruation (menarche), making it difficult to draw firm conclusions about how early development interacts with weight over time. Here, researchers evaluated multiple puberty milestones and tracked BMI at many points throughout childhood and adolescence. This allowed them to see the bigger picture: not only how early puberty is linked with later weight gain, but also when these changes start to emerge.
It’s important to note that the team found a different pattern in boys. Yes, boys who entered puberty early also tended to have higher BMIs in adolescence and adulthood—but this was largely explained by higher BMI in childhood. Once researchers adjusted for early childhood weight, the association between early pubertal onset and later BMI in boys nearly disappeared. By contrast, for girls, the relationship remained even when childhood BMI was taken into account.
What’s behind this difference? The experts involved suggest that biological sex may play a role. Hormonal shifts in female puberty could have a more profound impact on fat storage and metabolism compared to those experienced by boys. Oestrogen, for example, is known to influence fat distribution and deposition in the body. These hormonal changes may set up a trajectory where girls who mature early store more fat as they grow older—regardless of their initial weight status.
While the differences observed are statistically significant, the experts caution that they are relatively small on an individual level. No parent need panic if their daughter matures sooner than her friends. However, at the population level, the implications are worth considering. Early pubertal onset is becoming more common globally, possibly due to environmental factors like improved nutrition or increased rates of childhood overweight. If these trends continue, more girls may be at risk of carrying excess weight into adulthood—a factor associated with long-term health challenges such as cardiovascular disease and diabetes.
What can be done? Awareness is key. School nurses, doctors, and other health professionals should be mindful that girls who mature early might need additional support and monitoring as they progress through adolescence. Preventive measures—encouraging physical activity, healthy eating habits, and positive body image—could help offset the risks associated with early maturation.
One critical message from the researchers is that while timing of puberty is not something families can control, healthy habits established in childhood can make a difference. Encouraging children to stay active and eat well remains one of the most effective ways to reduce risk of obesity later on. Early intervention matters, especially for those showing signs of maturing ahead of schedule.
The Danish cohort study stands out because of its scale and design. Following children for over a decade allowed researchers to account for changes year by year, offering insights that cross-sectional studies simply cannot match. The use of multiple markers of pubertal development gave a nuanced understanding of how growth unfolds differently for each child.
Interestingly, the data also reinforce that girls’ biology may uniquely sensitise them to the effects of early hormonal changes on long-term weight regulation. In boys, pre-pubertal BMI explained most of the link between early puberty and later overweight status, suggesting that interventions targeting healthy weight in childhood may be particularly effective for them.
The study also underscores the importance of considering gender differences when designing public health strategies to address adolescent obesity. Girls may benefit from targeted interventions during the transition into adolescence, particularly if they show signs of maturing early.
As with all observational studies, it’s important to acknowledge limitations. The observed associations do not prove causation—other factors could play a role in both timing of puberty and future weight gain. For example, genetic predispositions or environmental exposures might influence both processes simultaneously. However, the large sample size and rigorous methodology lend considerable weight to the findings.
For parents and caregivers reading this news, context matters. Puberty is a complex process influenced by genetics, nutrition, environment—and now, we know more about how its timing can shape future health outcomes for girls especially. Keeping an open dialogue with children about bodily changes, supporting their mental health during what can be an emotionally turbulent time, and fostering healthy lifestyle habits provides a foundation for lifelong wellbeing.
For policy makers and educators, these findings point to opportunities for early identification and support for children at higher risk. Programs that encourage regular physical activity in schools and provide education on healthy eating can play a significant role in prevention efforts.
Researchers involved in this Danish study stress that their results should not be seen as cause for alarm but rather as an extra piece of information to inform care and prevention strategies. Early puberty is not destiny—its effects can be modified by lifestyle choices made in childhood and adolescence.
Looking ahead, further research is needed to untangle why these sex differences exist at the biological level and whether similar patterns hold true in other populations around the world. As scientists continue to map out how early life events shape long-term health trajectories, studies like this one offer valuable guideposts for families, clinicians and policy makers alike.
Early puberty appears to increase risk of being overweight later in life for girls—even those who start out at a healthy weight—according to new evidence from one of the largest studies of its kind. Boys follow a different pattern: their risk seems largely tied to their pre-pubertal BMI rather than when they start maturing physically. As childhood obesity rates remain high globally, these insights could help shape more effective prevention strategies tailored to each child’s needs.
