Hormone therapy for trans people has long been known to change body shape and body fat percentage. But by how much? And how much can be expected in the first year? A European study of 77 trans women and 73 trans men found out!
On average over the first year of hormones…
- Both trans women and trans men gained weight overall. On average they gained around 4-6 pounds (2-3 kg). Both groups started with a BMI around 24 (just barely between normal weight and overweight). For trans men, this weight gain tipped them into the “overweight” category. Trans women stayed in the “normal” weight category.
- Trans women gained body fat and lost muscle mass. Their body fat went up from 24% to 28%. They lost a kilogram (2.2 pounds) of muscle mass.
- Trans men lost body fat and gained muscle mass. Their body fat went down from 34% to 30%. They gained 5 kilograms (11 pounds) of muscle mass.
- There wasn’t much of a significant different in waist sizes.
It may be helpful to remember body fat percentage numbers. For cis women, 21-31% is considered a fit or normal range. For cis men, 14-25% is the fit or normal range. So the trans women in this study started out at an average body fat percentage and stayed there. The trans men in this study started off with too much body fat and stayed there.
During the first year of hormones it seems that around a 4% change in body fat can be expected. Trans men can gain quite a bit of muscle. Trans women will lose some muscle.
As a final note: this was a European study. The hormones used in Europe are different than the ones used in the United States. The results may not be applicable in the United States.
Want to read the study for yourself? The abstract is publicly available!