In a year‑long study of transgender people, estradiol lowered liver fat in trans women, while testosterone raised liver and visceral fat in trans men unless an aromatase blocker (anastrozole) was added. The GnRH agonist triptorelin was used to suppress natural hormones but didn’t directly cause the fat changes.

Liver fat content and visceral fat volume are associated with insulin resistance and cardiovascular disease and are higher in men than in women. To determine the effect of estradiol and testosterone treatment on liver fat and visceral fat in transgender persons. Open-label intervention study (SHAMVA) with a 1-year follow-up. Gender clinic in a hospital. 8 trans women and 18 trans men receiving hormone treatment. Trans women received an antiandrogen and after 6 weeks estradiol was added. Trans men were randomized to receive triptorelin, testosterone, and anastrozole for 12 weeks or triptorelin and testosterone for 12 weeks, followed by only testosterone until week 52. Liver fat content, visceral and abdominal subcutaneous fat volume, measured by magnetic resonance spectrometry or imaging at baseline, 6, 8, 18, and 58 weeks in transwomen or at baseline; at 6 and 12 weeks in trans men with anastrozole; and at 52 weeks in trans men without anastrozole. In trans women, liver fat content decreased by 1.55% (-2.99 to -0.12) after 58 weeks, compared to week 6. Visceral fat did not change. In trans men with anastrozole, the liver fat content and visceral fat volume did not change. In trans men without anastrozole, after 52 weeks, liver fat content increased by 0.83% (0.14 to 1.52) and visceral fat volume increased by 34% (16 to 51). Sex hormones regulate liver fat content and visceral fat in men and women.