When blood sugar levels get high, cells become insulin resistant. This keeps them from being flooded with glucose that they would then have to burn. The process of combining glucose with oxygen produces free radicals, and if cells did not become insulin resistant, they could be damaged by the free radicals. The ovaries are a special kind of tissue that nature makes sure always gets glucose.
The ovaries do not develop insulin resistance. They soak up more and more sugar and make more and more hormones. Ordinarily the ovaries make just a little testosterone. But when the rest of the body is insulin resistant, they make a lot. All the extra testosterone is a major factor in PCOS. But it's the insulin that causes the weight gain. That's because insulin doesn't just transport sugar. It also transports fat. Insulin resistance stops insulin from storing sugar, but insulin continues to store fat just fine. Sugar levels get higher and higher, the body tries to compensate by making more and more insulin, but it just stores more and more fat. If you want to lose the fat, stop eating sugar. The easiest way for women with PCOS to lose weight is to fight insulin resistance.
That can be done with medication, especially metformin, also sold under the trade name Glucophage. Insulin resistance also decreases when blood sugar levels decrease. That means cutting out calories, but especially the calories from sugar. One of the amazing things about PCOS is that sometimes women can get back into hormonal balance just by losing weight, and not a whole lot of weight. Losing even 5 pounds (2.5 kg) can nudge blood sugar levels just enough to stop the overproduction of testosterone that leads to many other hormonal imbalances. Most women make sustainable progress toward controlling PCOS by losing just half a pound of fat a week. That's the calorie equivalent of a dessert a day, or one large sugar-sweetened soft drink, or a bag of chips. This small change can be exactly what is needed not only to lose weight but also to bring the other symptoms of PCOS under control.