A 500 calories a day deficit works out to losing 1 pound a week, since a pound of fat is around 3,500 calories. So, your current diet of 1,300 is about a 500 point deficit. The recommended diet is 2,000/cal a day split 75/25 carbs to proteins. Some people dispute the carb intake, but that's what most dieticians say so take what you will. You are trying to kill your muscles though and your body loves muscles. Everyone's does. That's why they are targeted last to compensate for the energy your not getting by running a deficit.
Remember, when you lose weight by triggering your body to target muscles to burn energy, you also disrupt all other functions since your body plain slows your metabolism first to conserve energy rather then burn muscles. You don't want that. Not good for someone who is taking hormones which is a delicate thing in itself. Plus, it's not good for someone who wants to lose weight since the best way to lose weight is to do the opposite: speed up your metabolism.
But, I won't lie, by only eating 750 calories a day you should lose about 3/lbs a week. So, at 168 lbs so in 30 weeks, you will be down to 138. There probably wouldn't be any ill effects other then the diarrhea and fatigue you will experience while not eating. But I wouldn't do that since you're starting out HRT and that has its risks in itself and you are so young and you can lose the weight slowly. I'd stick to where you are at. In one year you will lose the amount of weight you would if you only consumed 750/cal a day for 30 weeks. But it will probably be way sooner with all the exercise you're doing. It sounds like you're doing great. I'd add a stationary bike or running as endurance training and fast-paced hardcore aerobics is the NUMBER 1 way for losing weight and the most healthy. That's key. But that's what I know about weight loss. I have done the whole not eating thing before to burn unwanted fat. It didn't work well only a little bit. And any that I did lose actually came back worse.
