Two-year study will examine how gender-affirming hormone therapy affects energy use and blood vessel function

A two-year study is set to investigate the impact of gender-affirming hormone therapy on energy use and blood vessel function in trans individuals. Building upon the previous Hormones and Health study (HHS), researchers from the LeiCeM Cluster of Excellence aim to delve deeper into the health effects of hormone therapy and its broader implications for understanding sex hormone function in the human body.

Led by PD Dr. Haiko Schlögl, the team will focus on three key areas: changes in body composition, energy expenditure, and blood vessel function. Utilizing advanced techniques such as a metabolic chamber to measure energy expenditure, detailed blood vessel tests, and MRI scans, the researchers hope to gain insights into how testosterone and estrogen affect the human body.

In the first phase of HHS, 40 trans individuals participated, with half being trans men and half trans women. Findings from this cohort, published in 2026, revealed that sensitivity to temperature changes increased in trans women during estrogen and testosterone-blocking therapy. While the reasons behind this adaptation are still being explored, the results suggest that hormone therapy can lead to significant physiological adjustments.

The upcoming study will employ more precise methods, including the assessment of brain structure changes using MRI. In collaboration with the Max Planck Institute for Human Cognitive and Brain Sciences, researchers aim to understand how hormone therapy may impact brain regions associated with gender differences. With a goal of improving patient care and safety, the findings could also help inform patients about potential risks and benefits of hormone therapy.