Lean women with PCOS are not metabolically in the clear

Polycystic ovary syndrome is one of the most common hormonal conditions in women, and obesity is known to influence how it shows up both clinically and metabolically. What has been missing is a large-scale pooling of data comparing obese and lean women with the condition across clinical signs, metabolic markers and hormones. That gap matters because lean women with PCOS are easily assumed to be the milder cases, an assumption that shapes how seriously their metabolic health gets monitored. This meta-analysis set out to quantify the differences between the two phenotypes properly.

The authors searched databases from inception through 31 December 2025 for studies reporting clinical, metabolic and hormonal profiles in obese and lean women with PCOS. Forty-two studies met the inclusion criteria, together covering 5,363 women, of whom 3,078 were obese and 2,285 were lean. Results were pooled using random-effects models, producing mean differences for continuous measures such as blood glucose and insulin resistance, and risk ratios for conditions such as diabetes and metabolic syndrome. The review was registered in advance on the PROSPERO database.

Obese women with PCOS fared worse on nearly every measure. Menstrual irregularity affected 84.7% versus 70.9% of lean women, acne 44.9% versus 36.8%, and biochemical hyperandrogenism 45.6% versus 31.8%. The metabolic gap was starker still: metabolic syndrome affected 51.2% of obese women against 11.9% of lean women, diabetes 8.6% versus 2.7%, and prediabetes 25.3% versus 12.1%, alongside higher insulin resistance scores, higher fasting glucose and worse cholesterol across the board. Crucially though, lean PCOS was not benign: these women still carried substantial burdens of menstrual dysfunction, excess androgens, insulin resistance, abnormal glucose handling and unfavourable blood fats.

The direction of these findings fits what clinicians have long suspected, but the authors note that differences between obese and lean PCOS had not previously been explored in large-scale meta-analyses, so this puts numbers on the gaps for the first time at this scale. Just as importantly, it documents that lean PCOS carries real metabolic risk rather than being a purely reproductive concern. The included studies followed people rather than assigning treatments, so the analysis cannot say obesity causes the worse profile rather than travelling alongside it. Substantial disagreement between studies on several outcomes also means the precise figures should be held loosely.

For a reader with PCOS, the message is twofold. Carrying excess weight alongside the condition is associated with considerably worse metabolic numbers, which is a reason to think of metabolic health as central to the condition rather than a side issue. Equally, a lean build is not an all-clear: insulin resistance, abnormal glucose handling and unfavourable cholesterol showed up at meaningful rates in lean women too. That is information rather than a protocol, but it argues against assuming the metabolic side of PCOS only applies to one body type.