Why Is My Hair Changing? Understanding the Hormones Behind Hair Growth

For many women, hair changes seem to happen overnight. Maybe your ponytail feels thinner than it used to. Perhaps you are noticing more hair in the shower drain, widening of your part, or hair that simply doesn't seem to grow the way it once did.

Hair loss and thinning become increasingly common during perimenopause and menopause, but hormones are not the only piece of the puzzle. Nutrient deficiencies, stress, inflammation, thyroid health, blood sugar balance, genetics, and overall health all play important roles.

The good news? Understanding what's happening is the first step toward supporting healthier hair.

Hair Is More Than Just Hair

Hair is not an essential organ. Your body doesn't prioritize growing thick, shiny hair if it's busy dealing with chronic stress, inflammation, nutrient deficiencies, or hormonal shifts.

Think of your hair like a "report card." When something is out of balance internally, your hair is often one of the first places you will notice it.

How Hair Actually Grows

Each hair follicle cycles through three phases:

• Anagen (Growth Phase): This phase lasts anywhere from 2–7 years. The longer a hair stays in this stage, the longer and thicker it can become.

• Catagen (Transition Phase): A short period where growth slows and the follicle begins to shrink.

• Telogen (Resting Phase): Hair rests for several months before shedding, making room for a new hair to grow.

Normally, we lose around 50–100 hairs per day. Problems arise when too many hairs enter the resting phase at once or when fewer follicles remain in the active growth phase.

Estrogen: The Hair Protector

Estrogen is one of the biggest supporters of healthy hair. It helps:

• Keep hair in the growth phase longer

• Improve blood flow to the scalp

• Support collagen production around hair follicles

• Maintain hair thickness and shine

During perimenopause and menopause, estrogen levels begin to fluctuate and eventually decline. As estrogen decreases, hair often becomes:

• Thinner

• Finer

• More fragile

• Slower growing

This is one reason many women notice changes in their 40s and 50s.

Progesterone: The Unsung Hero

Progesterone often doesn't receive as much attention as estrogen or testosterone, but it plays an important role in maintaining healthy hair. Among its many functions, progesterone may help reduce the activity of 5-alpha reductase, the enzyme that converts testosterone into dihydrotestosterone (DHT), a more potent androgen that can shrink susceptible hair follicles.

During perimenopause, progesterone is typically the first hormone to decline as ovulation becomes less consistent. This loss of progesterone may allow more testosterone to be converted into DHT, increasing the impact of DHT in women who are genetically susceptible to androgenetic hair loss.

While declining progesterone alone is rarely the sole cause of thinning hair, it can contribute to the hormonal environment that makes hair loss more likely—especially when combined with changes in estrogen, increased stress, thyroid dysfunction, inflammation, nutrient deficiencies, or genetics.

Testosterone Isn't the Enemy

Testosterone is often thought of as a "male hormone," but women naturally produce testosterone too, in much smaller amounts. In fact, it plays an essential role in women's health. Testosterone is made by the ovaries and adrenal glands, and small amounts are also produced in other tissues throughout the body.

Healthy testosterone levels help support:

• Muscle mass and strength

• Bone health

• Energy and motivation

• Mood and cognitive function

• Libido and sexual health

The issue is not testosterone itself. The body naturally converts a small portion of testosterone into another hormone called dihydrotestosterone (DHT) through an enzyme called 5-alpha reductase. DHT is a more potent androgen and is important for many normal body functions.

However, in people who are genetically susceptible, DHT can bind to receptors in the scalp and gradually shrink (miniaturize) hair follicles. Over time, hairs become finer, shorter, and less pigmented until some follicles stop producing visible hair altogether. This process is called androgenetic alopecia, or pattern hair loss.

Importantly, higher testosterone does not automatically mean higher DHT or hair loss. Many women with elevated testosterone, such as those with PCOS, never develop thinning hair, while others with completely normal testosterone levels do. That's because hair loss often depends less on the amount of testosterone circulating in the bloodstream and more on how sensitive the hair follicles are to DHT, along with genetics, inflammation, age, and overall hormone balance.

Thyroid Hormones Matter Too

Healthy thyroid function is essential for healthy hair. Both an underactive and overactive thyroid can contribute to:

• Increased shedding

• Dry, brittle hair

• Slower hair growth

• Thinning eyebrows (especially the outer third)

If hair changes are sudden or significant, thyroid function should be evaluated along with other possible causes.

Cortisol and Chronic Stress

Stress doesn't just affect how you feel, it affects your hair. Physical or emotional stress can push a large number of hairs into the resting phase, leading to noticeable shedding two to three months later. This is called telogen effluvium.

Common triggers include:

• Major illness

• Surgery

• Significant emotional stress

• Rapid weight loss

• Poor sleep

• Nutrient deficiencies

The encouraging news is that this type of hair loss is often temporary once the underlying stressor is addressed.

Insulin and Blood Sugar

Chronically elevated insulin can increase androgen activity in some individuals, particularly those with insulin resistance or polycystic ovary syndrome (PCOS).

Supporting healthy blood sugar through balanced meals, regular movement, strength training, quality sleep, and stress management benefits not only metabolic health but may also support healthier hair over time.

Nutrients Your Hair Depends On

Hair follicles require a constant supply of nutrients to grow.

Some of the most common deficiencies associated with hair loss include:

• Iron (especially low ferritin)

• Protein

• Zinc

• Vitamin D

• B vitamins (including B12 and folate)

• Biotin (only when truly deficient)

• Omega-3 fats

Before starting supplements, it's worth identifying whether a deficiency actually exists. More isn't always better, and excess supplementation can sometimes do more harm than good.

This is one of the reasons I recommend comprehensive blood work rather than guessing. When we work together, I evaluate these nutrients, along with thyroid function, inflammation, blood sugar regulation, liver health, hormones, and other key markers, to help identify why your hair may be thinning. Instead of taking a handful of supplements based on social media or internet advice, we can create a targeted plan based on what your body actually needs.

When Should You Seek Help?

If you're noticing:

• Hair shedding lasting longer than three months

• Rapid thinning

• Bald patches

• Scalp pain, redness, or scaling

• Hair loss along with fatigue, weight changes, or menstrual changes

It's worth speaking with your healthcare provider. Blood work, a medication review, and an assessment of your hormones, thyroid, iron status, nutrition, and overall health can help identify the underlying cause.

The Bottom Line

Hair health reflects what's happening inside the body.

While hormonal changes during perimenopause and menopause are common contributors to thinning hair, they're rarely the whole story. Nutrition, thyroid function, stress, inflammation, genetics, medications, and metabolic health all influence how your hair grows.

Rather than chasing miracle shampoos or expensive supplements, focus on supporting your overall health. Nourish your body with adequate protein, address nutrient deficiencies, prioritize sleep, manage stress, strength train regularly, and work with a knowledgeable healthcare provider to uncover the root causes of your symptoms.

Healthy hair starts with a healthy body, and while it takes time, supporting your health from the inside out gives your hair its best chance to thrive.

This article is intended for educational purposes only and should not replace individualized medical advice. If you're experiencing significant or persistent hair loss, consult your healthcare provider for a comprehensive evaluation.