Ans: Yes. Increased weight, especially around the tummy, is harmful to PCOS. When you have excess fat deposited around the abdomen, it is usually stored around important organs such as liver, the pancreas, and intestines. This fat releases a protein that increases insulin resistance, a condition where your body is not able to properly utilize the hormone named insulin.
Once the body cells become resistant to the action of insulin, the pancreas starts to over produce insulin to compensate for the reduced activity of the insulin. This extra insulin accumulates in the blood, leading to a condition called hyperinsulinemia. Excess insulin, in turn, causes a rise in the production of male hormones. And this leads to PCOS symptoms like the thinning of scalp hair (as seen among males,) excess hair growth (on arms, legs, face, chest, and back), acne, problems with glucose metabolism that can lead to type 2 diabetes and so on.
And the cause of all this is the fat stored around your belly. So you can well imagine the impact of losing weight in reversing PCOS.