Higher levels of the hormone leptin explain about half of why fat stored around the hips and thighs is linked to a lower risk of polycystic ovary syndrome, as leptin influences how the body manages energy and reproductive hormones.

Women of European ancestry with a genetic tendency to store more fat around the hips and thighs have a 15.5% lower risk of developing polycystic ovary syndrome, likely due to better insulin regulation and lower leptin levels, compared to those with different fat distribution patterns.

Metformin lowers leptin — the ‘satiety hormone’ — in obese women, even when they lose the same amount of weight as those not taking it, meaning it might directly affect how the body regulates hunger.

In individuals with polycystic ovary syndrome, a specific type of body fat around the hips and thighs appears to lower risk primarily by improving how the body responds to insulin, with fasting insulin levels accounting for most of this protective effect.