When Puberty Strikes Early or Late, Eating Disorder and Muscle Dysmorphia Risks Shift in Teens

Puberty is one of the most dramatic biological transformations the human body undergoes, and the precise moment it arrives may leave a lasting imprint on mental health. A large Danish population-based follow-up study, published in the Journal of Eating Disorders, has found that both earlier and later timing of pubertal milestones are linked to elevated odds of eating disorders in girls and muscle dysmorphia symptoms in boys. The research, based on 13,208 adolescents drawn from the Puberty Cohort within the Danish National Birth Cohort, adds an unusual dimension to a question scientists have long grappled with: not only when puberty begins, but how fast it unfolds. The answer, according to the data, is that timing matters far more than tempo.

The study was motivated by a persistent gap in the scientific literature. Previous research had suggested that girls who enter puberty earlier than their peers face a higher risk of eating disorders, but evidence in boys remained scarce, and the role of pubertal tempo — the speed at which the body progresses through pubertal stages — had never been clearly established in either sex. Eating disorders such as anorexia nervosa, bulimia nervosa, and binge eating disorder often have their onset during or shortly after puberty, making this developmental window a critical period for understanding how vulnerability emerges. Muscle dysmorphia, a condition characterized by a pathological preoccupation with perceived insufficient muscularity, has received even less attention in longitudinal designs, particularly in relation to pubertal development.

Methodologically, the study stands out for the density and quality of its pubertal data. Rather than relying on a single retrospective question about when puberty occurred, the researchers asked participants to self-assess Tanner stages — the standardized clinical classification of breast, genital, and pubic hair development — as well as age at menarche in girls, first ejaculation in boys, and voice break in boys. These assessments were repeated half-yearly throughout puberty, allowing the investigators to construct detailed individual trajectories of development. From these repeated measurements, pubertal timing and tempo were derived using a non-linear mixed effect growth model, a statistical framework capable of capturing the non-linear, S-shaped character of pubertal progression. Each participant was then categorized as having early or slow, average, or late or fast development for each milestone separately.

The outcomes were assessed at the 18-year follow-up of the Danish National Birth Cohort, combining two complementary data sources. Self-reported diagnoses of anorexia nervosa, bulimia nervosa, and binge eating disorder were collected by questionnaire, while clinically diagnosed anorexia nervosa and bulimia nervosa were identified through the Danish National Patient Register, a national database that captures diagnoses assigned in the Danish healthcare system. Muscle dysmorphia symptoms in boys were measured through self-report at the same follow-up. Associations were quantified as adjusted odds ratios with 95 percent confidence intervals estimated from logistic regression models, controlling for a range of potential confounding factors.

For girls, the pattern of results was strikingly bidirectional. Both early timing of pubic hair development, with an odds ratio of 3.06, and late timing, with an odds ratio of 2.43, were associated with significantly higher odds of clinically diagnosed anorexia nervosa compared with average timing. In other words, deviating in either direction from the population norm for pubic hair development roughly doubled or tripled the odds of receiving a clinical anorexia diagnosis. This U-shaped pattern challenges the simplistic assumption that only early developers are at risk, and it suggests that being out of synchrony with one’s peers — whether ahead of them or behind them — may itself be a source of psychological vulnerability.

The self-reported outcomes in girls painted a more differentiated picture. Late timing of breast development, pubic hair development, and menarche were each associated with markedly higher odds of self-reported anorexia nervosa, with late breast development showing the strongest association at an odds ratio of 3.86 and late menarche at 3.10. In contrast, early timing of these same milestones appeared to be associated with higher odds of binge eating disorder. This divergence hints at distinct psychological pathways: delayed puberty in girls may intersect with body dissatisfaction and restrictive eating as adolescents compare themselves to more physically mature peers, while earlier development, which brings rapid increases in body fat, may be channeled toward loss-of-control eating patterns characteristic of binge eating disorder.

The tempo analysis in girls revealed equally intriguing complexity. Fast tempo of pubic hair development was associated with higher odds of clinically diagnosed anorexia nervosa and self-reported binge eating disorder, but lower odds of self-reported anorexia nervosa, compared with average tempo. That a single characteristic of pubertal progression can point in opposite directions across related outcomes underscores how heterogeneous eating disorders are, and why no single developmental marker should be interpreted in isolation. For boys, the tempo findings were inconsistent overall, offering no clear evidence that the pace of puberty independently shapes muscle dysmorphia risk.

In boys, however, the timing findings were coherent and clinically meaningful. Early timing of first ejaculation was associated with higher odds of muscle dysmorphia symptoms, with an odds ratio of 1.96, and late timing of genital development was similarly associated, at an odds ratio of 1.88. This is among the strongest population-based evidence to date linking pubertal timing to muscle dysmorphia, a condition that has grown more visible with the rise of appearance-focused social media, supplement culture, and male body image concerns. The bidirectional pattern seen in girls was mirrored here: boys whose sexual development departed from the typical schedule, whether precocious or delayed, showed elevated odds of symptoms. Early-maturing boys may have experienced rapid muscular growth that drew attention and shaped expectations, while late developers may have felt their bodies lagged behind an idealized masculine physique.

Taken together, the study’s central conclusion is that pubertal timing, rather than tempo, showed the most consistent associations across clinically diagnosed and self-reported outcomes. The authors suggest that earlier and later pubertal timing may help identify adolescents who could benefit from closer monitoring for early signs of eating disorders and muscle dysmorphia symptoms. Because the Puberty Cohort assessed development half-yearly with a validated growth-modeling approach, and because clinical diagnoses were drawn from a national patient register rather than self-report alone, the study offers unusually robust triangulation of exposure and outcome. The availability of register-based diagnoses is a particular strength, since anorexia nervosa in clinical settings is far less susceptible to reporting bias than questionnaire-based assessment.

Nevertheless, some limitations warrant cautious interpretation. Pubertal milestones were self-assessed rather than rated by clinicians, and self-report of Tanner stages, while widely validated, carries some measurement imprecision. The outcomes were captured at age 18, and residual confounding by factors such as pre-pubertal body mass index, family environment, or genetic predisposition cannot be excluded. The modest number of clinically diagnosed cases, reflected in wide confidence intervals for some estimates, means the precise magnitudes of the associations should be treated as approximate. Even so, the scale of the cohort, the granularity of the pubertal assessments, and the convergence of self-reported and register-based outcomes make this one of the most comprehensive investigations of puberty and body image pathology conducted to date. The message for clinicians, parents, and educators is deceptively simple: adolescents whose puberty does not arrive on the typical schedule — in either direction — deserve particular attention in the years that follow, when disordered eating and distorted body image are most likely to take root.

Subject of Research: Pubertal timing and tempo in relation to eating disorders and muscle dysmorphia symptoms in Danish adolescents

Article Title: Pubertal development and eating disorders and muscle dysmorphia symptoms in adolescents: a Danish population-based follow-up study

Article References: Thomsen, A. M. L., Ernst, A., Strandberg-Larsen, K., Rask, C. U., Gaml-Sørensen, A., Benson, T. E., Arah, O. A., & Ramlau-Hansen, C. H. (2026). Pubertal development and eating disorders and muscle dysmorphia symptoms in adolescents: a Danish population-based follow-up study. Journal of Eating Disorders. https://doi.org/10.1186/s40337-026-01799-0

Image Credits: AI Generated

DOI: 10.1186/s40337-026-01799-0

Keywords: pubertal timing, pubertal tempo, eating disorders, anorexia nervosa, bulimia nervosa, binge eating disorder, muscle dysmorphia, Tanner stages, adolescents, Danish National Birth Cohort, body image, epidemiology