So, this is something I've been curious about for a while, but I've been unable to find any information on it. If someone has been on T for a good amount of time (1 Year or more) and they lose a large amount of weight (becoming severely underweight with low body fat percentage), would they theoretically lose all of the female pattern fat and then only develop fat in a male pattern once they start gaining weight again? It is a common thing for women who are anorexic to lose their breasts and develop a more androgynous figure, but because their hormones remain the same, they usually regain their female pattern fat (breast and hips) once they recover and gain the weight back. But, if you had a FtM who was already on hormones for a while before dramatically losing weight, it would make sense that when he gains the weight back, the testosterone would cause his fat to be distributed in a male pattern, theoretically permanently eliminating his breasts and hips. I'm sorry if this comes across as ignorant in any way, I'm just genuinely curious. I also am in no way trying to glorify eating disorders or propose this as a healthy method of transitioning.
I'm just gonna start saying this is extremely unhealthy and shouldn't be done
But to answer your question, yes. However the breast area that is breast tissue rather than fat won't change, so they won't fully disappear. Same with hips, all of it that is fat will disappear but most of us have larger hip bones than cismen, so it doesn't completely eliminate the hips. It doesn't make your body male (except for the penis), but it would get it pretty close.
I mean, the fat will redistribute to some degree even without extreme/disordered/unhealthy weight loss, so why bother with that step in the first place?
If it's an issue of breast size, what Dean said: it's unlikely that one's chest would become as flat as a cis-male's due to the functional breast tissue.
So basically, not a good way to avoid top surgery both because it doesn't work and because, well, people can die from that kind of weight loss.
I lost around 69-70lbs early on while taking hormones. I gained back 20-30. The weight has moved with a lot of it shifting to my belly. I noticed my arms and legs are leaner. At the same time, there's still a lot of fat in my hips.
I think that you would need to lose and gain for it to redistribute as opposed to staying the same weight. Or maybe it's significantly slower without losing/gaining.