PCOS and weight: what helps, and why it is harder.

What PCOS is

Polycystic ovary syndrome is one of the most common hormonal conditions in women of reproductive age. It is usually diagnosed when two of three features are present: irregular or absent periods, signs of raised male hormones (excess hair, acne, scalp hair thinning, or high testosterone on a blood test) and polycystic-looking ovaries on ultrasound.

The insulin connection

Most women with PCOS, including many who are not overweight, have insulin resistance. The body makes extra insulin to compensate, and high insulin drives the ovaries to produce more testosterone. That disrupts ovulation and makes fat, especially around the waist, easier to store. It is a cycle, and weight loss is one of the most effective ways to break it.

What weight loss does

• Losing 5–10% of body weight often brings back regular periods and ovulation
• It lowers testosterone, which over time improves acne and excess hair
• It reduces the risk of type 2 diabetes, which is much higher in PCOS
• It improves fertility and pregnancy outcomes

Medicines used in PCOS

• Metformin improves insulin sensitivity and can help cycles. Weight loss with it is modest.
• The combined pill regulates periods and reduces androgen symptoms, but it is not a weight treatment.
• GLP-1 medicines (for example semaglutide or liraglutide): meta-analyses of trials in PCOS suggest better weight loss and improved insulin resistance and menstrual regularity than metformin alone. The studies are still relatively small.

Planning around pregnancy

This matters. As weight falls and ovulation returns, fertility can come back quickly, sometimes before periods are regular. GLP-1 medicines are not used in pregnancy and are stopped well before trying to conceive, on medical advice. Tirzepatide can also make the contraceptive pill less effective. Every PCOS plan needs a clear contraception and conception plan from the start.