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

Earlier pubertal timing has been associated with eating disorders (EDs) in girls, but evidence in boys is scarce, and the role of pubertal tempo remains unclear in both sexes. We investigated associations of pubertal timing and tempo with EDs in girls and muscle dysmorphia symptoms in boys. Tanner stages, age at menarche, first ejaculation, and voice break were self-assessed half-yearly throughout puberty in 13,208 adolescents from the Puberty Cohort within the Danish National Birth Cohort (DNBC). Timing and tempo were derived using a non-linear mixed effect growth model and categorised as early/slow, average, or late/fast. Self-reported anorexia nervosa, bulimia nervosa, binge eating disorder, and muscle dysmorphia symptoms were obtained from the 18-year DNBC follow-up. Clinically diagnosed anorexia nervosa and bulimia nervosa were obtained from the Danish National Patient Register. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were estimated using logistic regression models. In girls, early (OR: 3.06 (95% CI: 1.07;8.74)) and late (OR: 2.43 (95% CI: 1.02;5.79)) timing of pubic hair development were associated with higher odds of clinically diagnosed anorexia nervosa compared to average. Late timing of breast development (OR: 3.86 (95% CI: 1.84;8.07)), pubic hair development (OR: 2.41 (95% CI: 1.07;5.44)), and menarche (OR: 3.10 (95% CI: 1.45;6.63)) were associated with higher odds of self-reported anorexia nervosa, whereas early timing of these milestones appeared to be associated with higher odds of binge eating disorder. In boys, early timing of first ejaculation (OR: 1.96 (95% CI: 1.06;3.63)) and late timing of genital development (OR: 1.88 (95% CI: 1.11;3.20)) were associated with higher odds of muscle dysmorphia symptoms. In girls, 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 to average. Findings for pubertal tempo in boys were inconsistent. Pubertal timing, rather than tempo, showed the most consistent associations across clinically diagnosed and self-reported outcomes. Earlier and later pubertal timing may help identify adolescents who could benefit from closer monitoring for early signs of EDs and muscle dysmorphia symptoms. Eating disorders often begin during and after puberty. Girls who go through puberty earlier than their peers may have a higher risk of eating disorders, but less is known about boys and whether the pace of puberty also matters. We examined whether timing and pace of puberty were associated with eating disorders in 13,208 adolescents from the Danish National Birth Cohort. Outcomes included clinically diagnosed anorexia nervosa and bulimia nervosa, self-reported anorexia nervosa, bulimia nervosa, and binge eating disorder in girls, and muscle dysmorphia symptoms in boys. We found that the timing of puberty showed more consistent associations with eating disorders than the pace of puberty. In girls, early and late pubertal timing were associated with clinically diagnosed anorexia nervosa. Late pubertal timing was associated with self-reported anorexia nervosa, whereas early pubertal timing appeared to be associated with binge eating disorder. In boys, early and late pubertal timing were associated with self-reported muscle dysmorphia symptoms. These findings suggest that puberty may be important for understanding when vulnerability to eating disorders in girls and muscle dysmorphia symptoms in boys emerges and may help identify adolescents who could benefit from closer monitoring.