Most women relate PCOS to being overweight or obese. This is a common misconception but the fact is that up to 50% of women diagnosed with PCOS are of normal weight or some are even underweight. Women with lean PCOS often go undiagnosed.
It is important to first understand the definition of lean. The Body Mass Index is a key index for relating weight to height. BMI is a person’s weight in kilograms (kg) divided by his or her height in meters squared.
BMI between 19 and 24 is considered Normal Weight
BMI between 25 and 29 is considered Overweight
The problem with BMI is that it does not give any information on Body Composition which can assess health and fitness levels. Lean women with PCOS could have measurable body composition differences.
Lean women with PCOS often go undiagnosed as typical tests may bring ‘normal’ results. Fasting Insulin, Glucose and HOMA Index will point to insulin resistance in lean women with PCOS. Research suggests that many lean PCOS women have normal fasting insulin but are more likely to have hyperinsulinemia after eating.
Why does polycystic ovary syndrome cause weight gain?
PCOS makes it more difficult for the body to use the hormone insulin, which normally helps convert sugars and starches from foods into energy. This condition called insulin resistance can cause insulin and sugar, i.e., glucose to build up in the bloodstream.
High insulin levels increase the production of male hormones called androgens. High androgen levels lead to symptoms such as body hair growth, acne, irregular periods and weight gain. Because the weight gain is triggered by male hormones, it is typically in the abdomen (abdominal fat). So, instead of having a pear shape, women with PCOS have more of an apple shape.
Does being Overweight Cause PCOS or Does PCOS Result in Obesity?
Both are possible. The link between PCOS and obesity is complicated. Signs and symptoms of polycystic ovarian syndrome begin for some females soon after they start having periods. Women with PCOS produce too much insulin, or the insulin they produce does not work as it should. The inability of insulin to function normally is one reason why women with PCOS tend to gain weight or have a hard time losing weight. For others, PCOS develops later on, following substantial weight gain. What is clear is that women affected by obesity have a greater risk for PCOS and women with PCOS have a greater risk for obesity.