Introduction
Excess visceral fat increases the risk of type 2 diabetes and cardiovascular disease and is influenced by sex hormones. Our aim was to investigate changes in visceral fat and the ratio of visceral fat to total body fat (VAT/TBF) and their associations with changes in lipids and insulin resistance after 1 year of hormone therapy in trans persons.
Methods
In 179 trans women and 162 trans men, changes in total body and visceral fat estimated with dual-energy X-ray absorptiometry before and after 1 year of hormone therapy were related to lipids and insulin resistance [homeostatic model assessment of insulin resistance (HOMA-IR)] with linear regression analysis.
Results
In trans women, total body fat increased by 4.0 kg (95% CI 3.4, 4.7), while the amount of visceral fat did not change (−2 grams; 95% CI −15, 11), albeit with a large range from −318 to 281, resulting in a decrease in the VAT/TBF ratio of 17% (95% CI 15, 19). In trans men, total body fat decreased with 2.8 kg (95% CI 2.2, 3.5), while the amount of visceral fat did not change (3 g; 95% CI −10, 16; range −372, 311), increasing the VAT/TBF ratio by 14% (95% CI 10, 17). In both groups, VAT/TBF was not associated with changes in blood lipids or HOMA-IR.
Conclusions
Hormone therapy in trans women and trans men resulted in changes in VAT/TBF, mainly due to changes in total body fat and were unrelated to changes in cardiometabolic risk factors, which suggests that any unfavorable cardiometabolic effects of hormone therapy are not mediated by changes in visceral fat or VAT/TBF.
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Objective
Transgender individuals sometimes report a lack of physical change during hormone treatment, such as alterations in muscle tone or fat distribution. Identifying characteristics of this subgroup could be a step towards individualizing hormone therapy in transgender individuals. Therefore, we study the variation of changes in body composition and characteristics associated with a lack of change.
Design and methods:
Body composition measures were recorded in 323 transmen and 288 transwomen at every visit from start of hormone therapy to a maximum of 24 months follow-up. Absence of change was defined as transmen with a decrease in lean body mass or transwomen with a decrease in fat percentage.
Results
A lack of change at 24 months was observed in 19 of 94 (20.2%) transmen and in 9 of 96 (9.4%) transwomen. The risk of not achieving change in body composition was related to lower testosterone levels and less suppression of LH in transmen (OR 0.67, 95% CI: 0.48-0.94 per SD increase in testosterone and OR 1.36, 95% CI 1.01-1.83 per SD increase in LH).
Conclusion
There is a large variation in body composition changes during hormone therapy, with a substantial proportion of individuals with no measurable effects. In transmen, serum testosterone and LH were associated with a lack of change, but serum hormone levels were not associated with body composition changes in transwomen. The results provide a rationale for individualizing hormone therapy in transmen, by considering individuals effects rather than solely relying on a standardized dosages of hormone therapy.
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