Eh, no, losing weight won't have any negative impacts. If you're Hispanic/Asian, you'll be amazed to discover how gifted you are under all that fat. If you manage to get to a healthy weight, you'll be most likely be amazed by how much of a great figure HRT will give you.
I'm sorry, but fearing that losing weight would affect your voice negatively or make hair grow is nonsense. If anything, your voice will get better because there'll be less wobbly stuff making its resonance deeper. And IF, I say IF your weight problem were bad enough to impede hair growth, believe me, you'd know it. Before hair is impeded, I'm pretty sure you'd have seen pretty awful things regarding your skin and circulation, for example.
Honestly, when you're into morbid obesity like that, there is nothing negative at all about losing weight. Yes, your Adam's Apple might show more, but a tracheal shave is nothing compared to the likely cost of the severe health problems your wieght would have eventually developed in you, at a 99 % chance.
Also, I don't want to push the knife into the wound, but I do not think there is anything worse for any gender than obesity. It's not even about gender anymore; it hinders your passing as a human, as in, very few people will not be repulsed by very excessive weight, and their very respect of your person is likely to fall without you or maybe even them noticing.
And uhm, that might hurt to hear, but if I were you, I'd focus on my weight more than transition at the moment. That's something you can do now, and at the point you're at, seriously, it's pretty much an immediate medical matter. As in, your life is probably in danger within the next 10 years. Not to mention I have a hunch that many doctors would find obesity, and even more so, morbid obesity, a strict counterindication to HRT.
Lastly, at such an extreme weight, if I were you, I would try to stop using such euphemisms as "a pretty big girl". It may make you feel better momentarily, but if you're anything like me, using euphemisms of that kind is like hiding your problems from yourself, like you're excusing them. You know about them deep down, but you push them out of your view on a day-to-day basis, reducing your likelihood and willingness to do something about it. At your weight, you're not pretty big - pretty big is 160-180 (unless you're very tall). You're morbidly obese. When I became obese, only when I started saying I was a ->-bleeped-<-ing fatass and a pig did I start losing weight. Of course, people vary, and for some doing such things might end with them harming themselves, becoming suicidal or becoming anorexic or bulimic.
I'm sorry, I'm being very harsh - dunno what's up with me tonight. I hope this will act like a motivation to health loss rather than an insult. :c If it had the wrong effect, then I'm sincerely sorry.
