Evaluating changes in body composition, bone mass, and metabolic profile in an animal model undergoing transfeminine hormone therapy and physical exercise

Abstract

Background & aims

Gender-affirming hormone therapy (GAHT) is essential for transgender individuals seeking body modifications. For transfeminine people assigned male at birth, GAHT typically involves a combination of antiandrogens and estrogens. Despite its importance, the scientific literature presents inconsistencies regarding the effects of these hormones on nutritional status, body composition, and biochemical markers. This study aims to evaluate the impact of estradiol enanthate and dihydroxyprogesterone acetophenide (E2EN/DHPA) hormonal treatment, in conjunction with resistive physical exercise, on body composition and metabolic profiles.

Methods

Twenty-eight male rats were divided into three groups: MO (control group, n = 8), receiving sesame oil vehicle; MH (n = 11), receiving E2EN/DHPA; and MEH (n = 9), receiving E2EN/DHPA along with physical exercise. The hormonal treatment was administered every ten days for two months, while the exercise regimen involved stair climbing with progressively increasing weights, performed five times weekly for seven weeks. Evaluated parameters included body mass index (BMI), body composition (fat and lean mass), bone mineral density (BMD), and lipid profile (triglycerides, HDL-C, LDL-C).

Results

The rats that received E2EN/DHPA showed significant changes in body composition and BMI, regardless of exercise. The MH group had increased body fat, while both the MH and MEH groups had decreased bone area and mineral content. However, BMD remained the same across all groups. Elevated triglyceride levels were observed, and the MEH group also had reduced LDL-C levels. HDL-C levels did not show significant variation.

Conclusion

The study's findings show similarities to changes seen in transfeminine individuals undergoing GAHT with estrogen and antiandrogens. These changes include decreased muscle mass, increased body fat, preserved bone mineral density, and elevated triglycerides. The study also found that resistance exercise positively impacted lipid profiles, particularly in reducing LDL-C. These results highlight the need for further research and comparative trials on hormone therapy regimens.