some people who go on metformin, have a side effect of weight loss but its a side effect of the drug, not what the drug is suppose to do for you (its an insulin sensitizing drug).
There is no drug on the market for PCOS that helps with weight loss - the metformin can help with blood glocose levels, but thats about all it can do you might louse on it, but keeping it off if you need to come off of it or once your body gets use to it is another matter
best solution is working with a dietition and finding a deal that works best for you
some find reduced carbs works best, others higher carb intake - its what you will find will work for you
some of us even have luck getting the weight off once we are on a form of BC (i lost over 100 pounds while on depo provera, and have kept it all off - lost 10 pounds in a month while on lupron and have kept it off) that helps to regulate our homone levels (there is a theory that once your hormones are balanced that weight loss will happen - its a theory that appered to work for me, since once they went back out of balance i've not been able to budge up or down).
Nyxks Musings nyxstium.info twitter.com/nyxks/
Cals Burned for 6 years = 2,359,000
6 years Deficit Total = 1,729,800
Should have lost: 250 to 495 pounds
Actual loss = 139 lbs and 50 inches from core
| Pounds lost: 51.1