I have both PCOS and Hashimoto's/subclinical hypothyroidism. I initially lost 40-45 lbs by exercising for 30-45 minutes almost every time before I ate (one or two big meals a day, spread out). I didn't count my calories, ate a low fat diet, and my TSH was about 5 at the time. I yoyo'd a little over a year after that, but I always maintained at least a 20-25 lb loss.
Now that I'm on 2000 mg of Metformin XR a day, it's a lot easier for me to maintain my loss and I'm slowly losing more. I even can do this with my TSH being 5+ (I'm in the process of getting my levo upped). I eat two normal sized meals, try to mostly pick healthy food (I don't count calories/carbs, though), and I do 30 minutes of exercise a day.
I've maintained this for 8 months and hope to continue on this path. Sticking with exercise is really important for me, but the Metformin has made maintenance a lot easier than before. Plus, I feel better in other ways too.
Height: 5'2.5 / Highest Weight: 186 lbs / Current Weight: 140 lbs