I'm not saying people should eat raw fat off of bacon. I'm saying that you body needs fat to distribute. If you don't eat any calories, and you exercise too much, your body will not form any shape. I have very many trans girl friends that range from very skinny to extremely voluptuous and it all adds up. The extremely skinny ones have no breast growth, while the very large ones have the largest breasts.
That's how boobs work, they're roughly 80% fat. They're similar to what men have because they're fat, all boobs are fat. The only difference girls have a bit more tissue, which you will grow regardless of your fat. But you won't grow much if you don't have fat. The tissue will grow in, but the boobs won't grow without fat.
You can get excellent results and still be at a healthy weight. You don't need to weigh 200+ lbs. But you also don't want your BMI to be 18 either, which sadly a lot of girls are just that skinny. Go for a well rounded diet, you're body needs all types of nutrients to grow. And don't deny yourself a bacon cheeseburger occasionally.
Edit: I am also gonna throw in here that women have bigger hips for child bearing. This is common knowledge obviously. But the hips act as a sort-of oven that keeps the womb warm. The extra hip padding is purely fat. A little bit of extra fat to push down there can give you a nice hourglass shape.
BUT, not all girls can grow hips or boobs, regardless of diet. Gaining some extra weight is not a guaranteed way to get boobs.There are a number of different reasons your fat can distribute in different places. Hormones is a big one, which is what we're talking about now. But stress is another large factor. If you are stressed from work, friends or family, don't get enough sleep, have a weird eating schedule, this is all stress on your body. Stress activates the adrenals which releases a hormone called cortisol. Cortisol is a fail-safe type of mechanism that causes your body to store body fat everywhere, but mostly around your mid-section and neck. Reducing stress will help immensely to gaining your desired body shape.
And to add to the comment of BMI, I'll just give you an example. I am 5' 7", 120lbs is at the absolute lower end of my "healthy weight" range, while 155lbs is at the absolute upper end of my "healthy weight" range. Why not aim for something in the middle, like 130-140lbs? You'll be in very good health and you'll have a little bit of extra body fat to distribute.
TL;DR?
- Reduce Stress
- Aim for a BMI in the middle of your healthy range range, around 22-23. This gives you extra fat to move around, while staying at a healthy weight.
- Boobs are 80% body fat, you will grow tissue regardless of body fat, but you need fat for them to grow to any real size.
- Extra body fat is not a guaranteed way to get an hour glass figure, or larger breasts, because not all girls can get them. But most girls are able to achieve this desired body shape, and the extra weight will help with that.