What Causes PCOS? Understanding the Symptoms, Different Types, and Why It Can Affect Thin Women Too
When most people think of Polycystic Ovary Syndrome, they picture weight gain, missed periods, and ovarian cysts. But the truth is, PCOS can look very different from one woman to another — and many women with PCOS are not overweight at all. At Modern Health MS, we often meet women who feel frustrated because they have symptoms of hormone imbalance, but they don’t fit the “typical” picture they’ve seen online. Some are very active, naturally thin, and still struggle with acne, hair loss, anxiety, irregular cycles, or severe PMS. Understanding what PCOS really is can help you make sense of your symptoms and know that there are options for treatment.
What is PCOS?
Polycystic Ovary Syndrome is a hormonal condition that affects how the ovaries communicate with the rest of the body. It can lead to imbalances in:ovulationinsulin signalingandrogen hormones (like testosterone and DHT)progesterone productionDespite the name, many women with PCOS do not have actual ovarian cysts. The condition is often more about hormone signaling than the presence of cysts.
Common Symptoms of PCOS
Symptoms can vary greatly, but common signs include:irregular or skipped periodsacnescalp hair thinninghair sheddingincreased facial or body hairfatiguebloatingdifficulty losing weightsugar cravingsmood changesanxietyinfertilityPMS symptomsSome women only experience a few symptoms. Others may have many.
Can Thin Women Have PCOS?
Yes. Absolutely.A woman can weigh 100 pounds and still have PCOS.This is sometimes called “lean PCOS,” and it can be missed because many people assume PCOS only happens in women who are overweight. Lean women may still have elevated androgen hormones, insulin dysregulation, or stress-related hormone imbalance.They often present with symptoms like: acne, hair loss, irregular cycles, elevated DHT, PMS, painful periods without significant weight gain.
What Causes PCOS?
There is not just one cause. PCOS often develops from a combination of genetics, hormone signaling, insulin imbalance, and inflammation.
1. Genetics
PCOS often runs in families. Some women inherit a tendency toward:higher androgen productioninsulin resistancemore sensitive hormone receptorsstronger conversion of testosterone into DHT
2. Insulin Resistance
Even thin women can have insulin resistance. Insulin is not only related to blood sugar — it also affects ovarian hormone production. When insulin levels are elevated, the ovaries may produce more androgens, which can worsen symptoms.
3. Elevated Androgens
Androgens are hormones like testosterone and DHT. Women naturally make them in small amounts, but when levels become elevated, symptoms can appear. DHT forms when testosterone is converted by the 5-alpha reductase enzyme: Testosterone→5α-reductaseDHT Testosterone 5α-reductaseDHT Elevated DHT may contribute to: hair thinning on the scalp acne oily skin unwanted facial hair
Different Types of PCOS
Many functional medicine providers recognize that PCOS can have different root drivers.
Often associated with:weight gainsugar cravingsfatigue after eatingirregular cycles
Often linked to:chronic stressanxietyelevated DHEA-Ssleep issueshair loss
Can be associated with:gut imbalancechronic inflammationbloatingfatigueskin issues
Post-Pill Hormone Imbalance:
Some women notice PCOS-like symptoms after stopping birth control as natural hormone signaling returns.
Why Hair Loss Happens in PCOS
Hair loss can be one of the most upsetting symptoms. When androgen hormones like DHT are elevated, they can cause scalp hair follicles to gradually shrink. This may lead to increased shedding widening part line thinning at the crown, reduced hair density. The earlier hormone imbalance is addressed, the better chance the follicles have to recover.
The Good News: PCOS Can Be Treated
The key is understanding what is driving your symptoms. Treatment may include: supporting ovulation, improving insulin sensitivity, lowering androgen effects, reducing inflammation, restoring nutrient deficiencies, balancing progesterone, improving gut health. Because every woman’s hormone story is different, treatment should be personalized — not one-size-fits-all.
Looking for Answers?
If you are experiencing symptoms like hair loss, fatigue, acne, irregular periods, or PMS but have been told your labs are “normal,” there may still be an underlying hormone imbalance worth exploring.At Modern Health MS, we help women uncover the root causes of symptoms and create a personalized plan to restore balance.
