“Gender-affirming” hormone therapy increases BMI.
A 2025 systematic review and meta-analysis1 of 29 studies (28 included in meta-analysis) involving 2,674 individuals found that “gender-affirming” hormone therapy led to statistically significant body mass index (BMI) increases. The mean age across studies ranged from 16 to 56 years, and no prior puberty suppression was reported before the initiation of GAHT. The researchers excluded studies with adolescent samples or with pubertal suppression prior to hormone therapy. Natal males receiving feminizing hormones experienced an average BMI increase of 0.55 kg/m², while natal females receiving masculinizing testosterone showed a larger average increase of 0.92 kg/m². The study authors noted these represent modest weight gains with moderate certainty of evidence, though they concluded the changes reflect expected hormonal effects rather than pathological outcomes.