I weighed about 185lbs in early 2008. I started exercising regularly and had set a goal of not allowing myself to start HRT until I was at 150lbs. So I had my work cut out for me.
My exercising routine was 4-5 times per week doing mainly cardio activities such as running or biking. I didn't drastically change my eating habits, but I did cut out all alcohol and soda/pop. I dropped my weight into the upper 160's within a few months. I also started seeing a trans-friendly family practice doctor over the summer of 2008 and have been diagonsised with high blood pressure. Well, the doctor knows that I am trans and therefore with the high blood pressure, prescribed Spiro because it has the dual effect for reducing high blood pressure and is also used as a Testerone blocker. Spiro is a diuretic which is another name for a "water pill", thus helps a person reduce their water content in their body, thus one of the side effect of more frequent urination. My weight has since decreased into the mid 150's since starting Spiro only 3 months or so ago.
It took me some tremendous will power to give up soda/pop, but everything else has been fairly easily. You need to determine what's important, and if losing weight and getting into the shape you desire for your female form, then you need to resist the urges and cravings of your favorite snacks and find some time to get started in a workout routine. I don't specifically know off hand what the SRS requirements are, but I would have to concur with one of the previous responders that I believe there are guidelines, so that will need to be an eventual goal. Don't necessarily start out with that as your goal though because it is a huge undertaking to lose that much weight in a timely fashion, but rather set some incremental goals along the way and maybe reward yourself as you reach them. For me, my next goal is the 150lbs mark and then I will start on the "E".
Good luck with your weight and many best wishes throughout the upcoming holiday season. Keep strong and stay true to your goals.
Regards, Jennifer R.