And for some women, metformin makes weight loss easier. Metformin is a drug that makes cells all over the body, except the ovaries, more sensitive to insulin. The more sensitive the body is to insulin, the less the pancreas has to make to keep blood sugar levels normal. The significance of insulin sensitivity in losing weight in order to manage PCOS is this: Insulin doesn't just transport sugar out of the bloodstream. It also transports fatty acids out of the bloodstream. In fact, insulin is 300 times more efficient at transporting fat out of the bloodstream to store in fat cells than it is at moving blood sugar. When cells become "insulin resistant," they only resist incoming blood sugar. They don't resist fat. All that insulin that a woman's body isn't using to transport glucose can be used to stuff female fat cells with just as much as they can hold. Women still have to overeat to gain weight. High insulin levels just guarantee the formation of fat.
Metformin stops the cycle of high blood sugars, which cause greater appetite, which leads to more eating, which leads to higher blood sugars, which leads to higher insulin resistance, which leads right back to higher blood sugars, greater appetite, even higher insulin levels, and more insulin resistance. Once your blood sugars get out of balance, the problem gets worse and worse. Metformin helps women pull out of this downward spiral. But metformin has a special benefit to the ovaries. The ovaries can't resist insulin. They are programmed by nature always to accept sugar from the bloodstream (like cells in the brain). When sugar floods the ovaries, they make large amounts of the hormones they usually make in small amounts, like testosterone. When women get their blood sugar levels down, they also get their testosterone levels down. Appetite becomes easier to control, weight is loss, and a downward spiral to ever greater hormonal imbalance is replaced by an upward spiral to ever greater reproductive health.