You might notice more hair than usual in the shower, thinning around your temples, or your ponytail feeling smaller than it used to. Sometimes it seems to happen suddenly, while other times it shows up gradually over time.
A lot of people assume hair loss is purely genetic. And while genetics can definitely play a role, we often see other factors involved as well.
Things like hormone changes, thyroid function, iron levels, and nutrition can all influence how healthy your hair follicles are.
What you might not know? Hair loss is often a signal that the body might need support somewhere else.
Hair Growth Is Closely Connected to Overall Health
Hair follicles are actually very active parts of the body. They require a steady supply of nutrients, hormones, and oxygen to grow strong, healthy hair.
When the body is under stress, dealing with nutrient deficiencies, or experiencing hormone shifts, the hair growth cycle can change. This is why people sometimes notice increased shedding after things like illness, major stress, pregnancy, or hormone changes.
When the body is trying to rebalance itself, hair follicles are often one of the first places we see changes.
Hormones and Hair Loss
Hormones play a major role in hair growth for both men and women.
In men, hair thinning is often linked to dihydrotestosterone (DHT), a hormone derived from testosterone. Over time, sensitivity to DHT can cause hair follicles to shrink, which leads to thinning along the hairline or crown.
In women, hormone changes can also influence hair growth. We often see hair thinning during times when hormones are shifting, such as:
• After pregnancy
• During perimenopause or menopause
• With conditions like PCOS
• During periods of high stress
These hormone shifts can push more hair follicles into the shedding phase of the hair cycle.
Thyroid Health and Hair Thinning
The thyroid plays an important role in regulating metabolism throughout the body, including the health of hair follicles. When thyroid hormones are out of balance, hair growth can slow and shedding may increase.
Both underactive thyroid (hypothyroidism) and overactive thyroid (hyperthyroidism) can contribute to hair thinning. Sometimes hair loss related to thyroid changes appears alongside other symptoms like:
• Fatigue
• Dry skin
• Brittle nails
• Feeling unusually cold
• Difficulty with energy
When these patterns show up together, it can be helpful to take a closer look at thyroid function.
Iron Levels and Hair Loss
Low iron is one of the most common contributors to hair thinning, especially in women. Hair follicles need oxygen and nutrients to grow properly, and iron helps carry oxygen through the bloodstream. When iron stores are low, hair follicles may shift into the shedding phase more quickly. This can happen for a number of reasons, including:
• Heavy menstrual cycles
• Pregnancy or postpartum changes
• Low dietary iron intake
• Digestive issues that affect absorption
Checking ferritin levels, which reflect iron stores in the body, can often provide helpful insight when hair shedding is happening.
Do GLP-1 Medications Affect Hair Loss?
Another question that has come up recently is whether GLP-1 medications can affect hair.
These medications, often prescribed for diabetes or weight management, have become much more common in recent years. As more people use them, some have noticed increased hair shedding.
Research suggests the medication itself may not directly cause hair loss. Instead, rapid weight loss can sometimes trigger a temporary shedding pattern called telogen effluvium.
This type of hair loss can also happen after illness, surgery, pregnancy, or periods of significant stress. Rapid weight loss can also affect things like:
• Protein intake
• Iron levels
• Nutrient intake
• Overall metabolic stress
All of these factors can influence the hair growth cycle.
Testing That Can Help Identify the Root Cause
When someone comes in concerned about hair loss, one of the most helpful steps is often looking a little deeper at what’s happening internally.
Some of the most common lab markers evaluated for hair loss include:
- Iron and ferritin levels: Ferritin helps measure the body’s iron stores. Even when iron levels appear normal, low ferritin can sometimes contribute to hair thinning.
- Thyroid markers: Testing often includes TSH, Free T3, and Free T4 to evaluate how well the thyroid is functioning.
- Sex hormones: Hormone testing may include markers like testosterone, estrogen, progesterone, and DHEA to see whether hormonal shifts could be contributing to hair loss.
- Vitamin levels: Nutrients like vitamin D, B12, and folate can influence hair follicle health.
- Blood sugar and metabolic markers: Tests like fasting insulin and HbA1c can sometimes reveal metabolic stress that may indirectly affect hair growth.
Looking at these markers together often helps create a clearer picture of what might be contributing to hair thinning.
Nutrition and Hair Growth
Hair growth requires a steady supply of nutrients. When the body isn’t getting enough of certain vitamins or minerals, hair health can be affected.
Some of the most important nutrients for hair include:
- Protein: Hair is largely made of keratin, a type of protein. Getting enough protein helps support hair strength and growth. Good sources include eggs, fish, poultry, legumes, and nuts.
- Iron: Iron-rich foods like red meat, spinach, lentils, pumpkin seeds, and legumes support oxygen delivery to hair follicles.
- Healthy fats: Omega-3 fats found in salmon, walnuts, and flaxseeds support scalp health and help balance inflammation.
- B vitamins: These vitamins support energy production and hair follicle function. Leafy greens, eggs, whole grains, and legumes are good sources.
Supplements That May Help
When nutrient gaps are present, targeted supplements may help support hair growth. For many women, prenatal vitamins can be helpful because they often contain several nutrients important for hair health, including iron, folate, and B vitamins.
Other supplements that may be considered include:
• Iron (when levels are low)
• Zinc
• Biotin
• Vitamin D
• Omega-3 fatty acids
It’s usually best to look at lab results first so supplements can be tailored to what the body actually needs.
Looking at the Root Cause
Hair loss can feel discouraging, but it can also provide helpful clues about what may be happening in the body.
Instead of focusing only on the hair itself, functional medicine looks at the bigger picture. Hormone balance, thyroid health, nutrient levels, stress, and metabolism all influence the environment where hair follicles grow.
When those systems are supported, many people begin to see gradual improvements in hair growth over time.
If you’ve been noticing hair thinning or increased shedding, taking a closer look at what’s happening inside the body can often be an important first step.
References:
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Guo, E. L., & Katta, R. (2017). Diet and hair loss: Effects of nutrient deficiency and supplement use. Dermatology Practical & Conceptual, 7(1), 1–10.
Harrison, S., & Sinclair, R. (2003). Telogen effluvium. Clinical and Experimental Dermatology, 27(5), 389–395.
Messenger, A. G., & Sinclair, R. (2006). Follicular miniaturization in androgenetic alopecia: Pathophysiology and treatment. Journal of Investigative Dermatology Symposium Proceedings, 11(1), 14–17.
Rushton, D. H., Norris, M. J., Dover, R., & Busuttil, N. (2002). Causes of hair loss and the developments in hair rejuvenation. International Journal of Cosmetic Science, 24(1), 17–23.
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