BMI and PCOS
Polycystic ovary syndrome (PCOS) affects around one in ten women and is closely linked with insulin resistance. BMI is recorded at most PCOS appointments, and guidelines note that even a modest weight loss of 5% can make periods more regular and improve symptoms in women with a higher BMI. Many women with PCOS have a healthy BMI, though, so BMI is only one part of the picture.
Where the BMI index comes from
The formula was described in the 1830s by the Belgian statistician Adolphe Quetelet, who noticed that adult weight rises roughly with the square of height. It was renamed “body mass index” by the physiologist Ancel Keys in 1972, and the World Health Organization adopted today’s cut-offs — 18.5, 25 and 30 — in the 1990s. That long history is why the same index is used by doctors, insurers and researchers around the world.
Healthy weight in kilograms by height
The weight in kg at the bottom (BMI 18.5) and top (BMI 24.9) of the healthy range, and where obesity begins (BMI 30):
| Height | BMI 18.5 | BMI 24.9 | BMI 30 |
|---|---|---|---|
| 150 cm | 41.6 kg | 56.0 kg | 67.5 kg |
| 155 cm | 44.4 kg | 59.8 kg | 72.1 kg |
| 160 cm | 47.4 kg | 63.7 kg | 76.8 kg |
| 165 cm | 50.4 kg | 67.8 kg | 81.7 kg |
| 170 cm | 53.5 kg | 72.0 kg | 86.7 kg |
| 175 cm | 56.7 kg | 76.3 kg | 91.9 kg |
| 180 cm | 59.9 kg | 80.7 kg | 97.2 kg |
| 185 cm | 63.3 kg | 85.2 kg | 102.7 kg |
| 190 cm | 66.8 kg | 89.9 kg | 108.3 kg |
| 195 cm | 70.3 kg | 94.7 kg | 114.1 kg |