In a Danish study of transgender teens, many were already overweight or had bad cholesterol before any hormone treatment. Using a GnRH‑blocking peptide (like gonadorelin) alone slightly lowered weight but didn’t consistently change BMI or blood fats. Adding sex hormones later caused boys to lose some good cholesterol (HDL) and gain triglycerides, while girls saw a rise in HDL. Overall, the peptide itself isn’t a major driver of weight or lipid problems, but the added sex steroids do shift blood‑fat profiles.

Cardiovascular health of the transgender population receiving hormone therapy (HT) has been a concern. To investigate weight, BMI, and lipid profiles in a national cohort of transgender adolescents starting HT before 18 years of age. In this observational study, 164 trans boys and 55 trans girls were followed longitudinally during HT. Gonadotropin-releasing hormone analog (GnRHa) was initiated either before or alongside sex steroid therapy. Anthropometry and lipid profiles were analyzed at the start of HT and at routine visits. Before HT, overweight (BMI 1-2 standard deviation score (SDS)) and obesity (BMI ≥2SDS) were found in 26.8% and 22.0% of trans boys, and in 5.7% and 5.7% of trans girls, respectively. BMI SDS correlated positively with total cholesterol, low-density lipoprotein (LDL), and triglycerides, and negatively with high-density lipoprotein (HDL). In trans boys and girls, high percentages had lipids above normal reference intervals; total cholesterol (12.5% and 6.1%), LDL (21.8% and 12.5%), and triglycerides (3.4% and 6.3%), and HDL below normal reference intervals (9.0% and 18.4%), respectively. During GnRHa monotherapy, there was a tendency for declining weight SDS, but BMI SDS, and lipid profiles did not change consistently. After the initiation of sex steroids, weight SDS, BMI SDS, and HDL decreased along with increased triglycerides in trans boys, and increased HDL in trans girls. Overweight, obesity, and dyslipidemia were common in transgender adolescents before HT was initiated. BMI did not deteriorate, but dyslipidemia worsened slightly during sex steroid therapy in trans boys but not in trans girls.