How can a teenager lose breast fat?

It is not really possible to change the breast for FTM without surgery.  You need to find a surgeon that specializes in the procedure and speak to them.  At your young age they will require that you speak to a counselor to help you make decisions.

Hi there over in Greece.Your simple request in this forum is both brave, and remarkable. At 14, you're a kid still, and to be confident of your identity at your age is pretty amazing and even maybe premature. I wish you very well with your journey and navigation of the many issues in front of you, and I hope that those around you will be supportive.To your question:  At 14 almost certainly your breasts will continue to enlarge some more yet. Unfortunately there is no method of losing breast tissue through diet or exercise, unless you're overweight in which case weight loss will reduce the fat component of the breast, but not the glandular tissue of the breast which will not disappear with weight loss.Here is my advice to you:  The sooner you are able to tell your parents or close advisors the better.  You're going to need a lot of support, psychological help and expert medical assistance.  If indeed you are FTM, (and while I know you think you are, please understand you're 14 and I suspect can't yet truly be sure), then expert medical advice may be the best bet for you in minimising the effects of female secondary sex physical characteristics.All the very best.

I agree with Dr. Webster. It may be premature to decide that you are transsexual. I suggest that you confide this thought to your physician, and perhaps to your parents, if they are likely to be supportive. Unfortunately there are no exercises that will make your breasts smaller and at age 14 they may well get larger with time.I wish you well and hope that things work out for you.