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Get The Skinny On ‘Lean PCOS’!

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Reviewed by Veera Reproductive Care
  • 24 April
  • 3 min read
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Unlike what you may have heard, you can be thin and still have PCOS! Read on to know more about ‘lean PCOS’ and its risk factors.

Lately, it seems like every month comes with a new health buzzword! So, this time we’re digging into ‘lean PCOS’. If you’re familiar with PCOS or polycystic ovarian syndrome, you’ve likely come across this term before. Now, what exactly is lean PCOS and how is it different from regular PCOS? Let’s find out.


The PCOS and obesity connection


PCOS is one of the most common hormonal disorders, affecting several women between puberty and menopause. When it was first identified by scientists Stein and Levinthal, it was associated with irregular periods, obesity and hirsutism (abnormal male pattern hair growth). After more research was done, experts settled on the Rotterdam Criteria for diagnosing PCOS. The Rotterdam Criteria states that to have PCOS, a woman must have 2 out of 3 of the following criteria:

  • Irregular periods (see our article about regular periods)
  • Excessive male hormones (e.g., seen as abnormal hair growth or acne)
  • Many small cysts in the ovaries

Obesity, while highly associated with PCOS, was never included in the criteria. Further, it was discovered that even thin women could meet the above criteria and have PCOS. In fact, approximately 20% of women with PCOS are lean or have a normal BMI.


How do we define lean?


Lean refers to a person with a BMI of less than 25. BMI stands for Body Mass Index, which is calculated using your weight and height. There are several calculators available online to calculate this. For example, someone who is 5 ft 4 in and weighs 60 kg has a BMI of 22. Based on your BMI, you will be classified into either underweight, average weight or lean, overweight or obese..
BMI Classifications:
Underweight = <18.5
Normal weight = 18.5-24.9
Overweight = 25-29.9
Obesity = >30
Therefore, someone who has a normal BMI (18.5-24.9) and has PCOS is said to have ‘lean PCOS’. But it is not a distinct category of PCOS.


How does PCOS affect lean women?


Lean women with PCOS have many of the same symptoms as overweight and obese women, such as difficulty losing weight and are prone to insulin resistance and metabolic disorder. It’s important to know that PCOS is caused by hormonal imbalance, which still occurs in lean women. PCOS also puts them at risk for Type 2 diabetes, cardiovascular disease, infertility and endometrial cancer, but to a lesser degree than their obese counterparts. Studies are still in progress comparing the differences between lean and obese women with PCOS, but the jury remains out.

We know that lean women with PCOS, especially those with insulin resistance, will have more difficulty maintaining their weight than their non-PCOS counterparts. Doctors also prescribe them lifestyle interventions such as a healthy diet, exercise and oral contraceptive pills. But, of course, weight loss isn’t a priority treatment for slim women with PCOS as it is for their obese counterparts.

Now you know that, ‘Lean PCOS’ is just a buzzword referring to the 20% of women with PCOS who have a normal BMI. So, if you’re a thin woman with PCOS-like symptoms, don’t simply brush them off. If left untreated, PCOS can lead to severe health conditions that are difficult to manage. We recommend consulting with a doctor who can diagnose it correctly and provide you with custom treatment.





Reviewed by Dr. Shailly Prasad, MD/MBA, Resident Physician, Obstetrics & Gynaecology.


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