The process of transitioning from female to male typically takes a significant period of time. Transgender men may wish to significantly reduce breast size as part of this transitioning process. Gender reassignment surgery typically focuses on the breast and genital areas, altering anatomical traits from a function and aesthetic typically viewed as female to those viewed as male. Breast reduction or removal surgery is typically part of gender reassignment surgery. However, if you do not wish to undergo surgery -- or if you do not have insurance coverage to pay for such surgery -- there are nonsurgical options that may help reduce your breast size.
Female breasts are made up mostly of fatty tissue, connective tissues and milk glands. Because your breasts have a higher fat content than, for example, your face or your legs, overall weight loss can reduce the size of your breasts faster than other areas of your body. The correlation between body fat proportion and breast size is one of the reasons big breasts are more commonly found on overweight women -- lean women typically have smaller breasts.
Many female-to-male transgender people use androgen hormones such as testosterone to help affect physical and other changes. If you are taking an androgen such as testosterone, this hormone may cause changes to your breast size and shape. Breasts may become smaller or more elongated. Testosterone can also cause a broadening of the shoulders, which would make your breasts look smaller by comparison. Although some people experience weight gain with androgen use, others experience overall weight loss. If you lose weight overall, your breast size will also likely decrease significantly.
One way you can lose weight from your body -- and therefore fat from your breasts -- is through creation of a calorie deficit. Simply put, this means that the number of calories you burn in a day will be greater than the number of calories you consume. A calorie deficit can be created by restricting how much you eat, by burning excess calories through exercise, or a combination of both. One pound of body fat contains 3,500 calories, so you can lose a pound in a week by creating a daily deficit of 500 calories -- the exercise equivalent of walking approximately five miles.
Although weight loss, hormone therapy or an exercise-induced calorie deficit may lead to a reduction in the size of your breasts, none of these methods is proven to directly cause changes in breast size. Breast reduction surgery is the only certain method of making your breasts smaller. When dieting for overall weight loss, maintain a minimum safe daily calorie intake of 1,200 calories for a female or 1,800 calories for a male. Consult your doctor for medical advice before making significant dietary or lifestyle changes.