Understanding Hair Loss: Why It Happens and What Type You May Have
To understand why you are losing hair, it is first and foremost important to understand that not everyone loses hair in the same way.
The most common form of hair loss is male pattern baldness (androgenetic alopecia), which to some degree affects up to 40% of men by age 30 and up to 80% by age 70. Other common types of hair loss include telogen effluvium, alopecia areata, and traction alopecia.
So how do you know which one you have?
First of all, you should always speak to a doctor if you experience hair loss that concerns you. However, to give you a general idea of what characterizes the different types of hair loss, a short summary follows.
Androgenetic Alopecia (AGA) – Male Pattern Baldness
Distinctive features
The pattern
AGA usually follows a recognizable pattern. It often begins with a receding hairline (forming an “M” shape) or thinning at the crown (the so-called “monk’s spot” — or, as I like to call it, the helicopter pad).
That said, hair loss does not always present as clearly defined bald spots. Some people experience diffuse thinning across the top of the scalp, while the hair on the sides and back typically remains thick and unaffected.
Miniaturization
Look at the hairs you shed. Are some of them becoming shorter, thinner, and almost transparent compared to the hair on the back of your head? This gradual “shrinking” of the hair shaft is a defining sign of AGA.
The Hamilton–Norwood Scale
Doctors use this visual scale (stages 1–7) to classify the progression of male pattern baldness. If your hair loss follows these stages, it is almost certainly genetic.
The genetic aspect
Look at your father, grandfather, and family in general. Is there a history of hair loss that matches the signs above? Androgenetic alopecia is hereditary, and family history is often an early indicator of how your hair loss may progress.
Key facts
-
The most common form of hair loss
-
To some extent reversible, especially if treated early
(Insert image of the Norwood scale here)
Telogen Effluvium
Telogen effluvium is, in most cases, a temporary form of hair thinning caused by a “shock” to the system. Common triggers include:
-
High fever or illness
-
Surgery
-
Extreme or prolonged stress
-
Rapid weight loss
-
Certain medications
-
Nutritional deficiencies (iron, biotin, vitamin D)
-
Inflammation
Unlike male pattern baldness, telogen effluvium causes diffuse thinning across the entire scalp rather than a specific pattern.
Reversibility:
Depending on the trigger, this condition can be close to fully reversible — but not always.
Alopecia Areata
Alopecia areata is an autoimmune condition in which the immune system attacks the hair follicles. This leads to sudden, smooth, round bald patches, often appearing without warning.
Traction Alopecia
Traction alopecia is caused by chronic physical stress on the hair, such as:
-
Tight hairstyles (braids, man buns, ponytails)
-
Excessive chemical processing
Reversibility:
This type of hair loss may be reversible, but not always. It depends on how long the damage has been ongoing and whether fibrosis (scarring) has occurred.
If you are uncertain about the cause of your hair loss, please consult a medical professional.
I am also available for free advice and guidance if you are having trouble finding a doctor or feel that you haven’t received satisfactory answers from medical personnel. In that case, feel free to contact me directly on Instagram @markusdegerman1 or @pausehaircare, or via the email feature on this page.
Focus Going Forward: Androgenetic Alopecia
Since androgenetic alopecia is by far the most common cause of male hair loss, the remainder of this article will focus specifically on this condition.
What Causes Male Pattern Baldness (Androgenetic Alopecia)?
The main factor: hormones — specifically DHT
Based on current scientific understanding, male pattern baldness is primarily a hormone-driven condition. More specifically, it involves the testosterone derivative dihydrotestosterone (DHT).
The DHT hypothesis suggests that DHT binds to hair follicles in genetically susceptible individuals, causing them to shrink (miniaturize) over time and eventually stop producing hair altogether.
DHT is 3–8 times more potent than testosterone in terms of androgenic activity (although it is not proven to be 3–8 times more effective for building muscle — so take it easy).
How Do We Know DHT Is Involved?
The Castrati observation
Historically, it was observed that men castrated before puberty did not develop male pattern baldness. This demonstrated that hormones are necessary for hair loss to occur.
(James B. Hamilton, 1960)
5-alpha-reductase deficiency (1977)
In the late 1970s, researchers identified a genetic mutation in individuals from Papua New Guinea who lacked the enzyme 5-alpha-reductase — meaning they could not convert testosterone into DHT. These individuals did not develop male pattern baldness. This discovery shifted the focus from “hormones in general” to DHT specifically.
Finasteride and clinical trials
During clinical trials for Proscar (finasteride 5 mg), originally developed to treat enlarged prostate, researchers observed that men experiencing hair loss showed noticeable improvements in hair thickness.
In 1992, finasteride was approved for prostate treatment, and five years later, Propecia (finasteride 1 mg) was launched specifically for hair loss. Clinical trials showed that finasteride slowed, stopped, or even reversed hair loss in 80–90% of men with AGA — numbers that have remained consistent across numerous studies since.
Today, it is widely accepted that finasteride halts hair loss in approximately 4 out of 5 men with androgenetic alopecia.
DHT exposure studies (2006)
In laboratory studies where hair follicles were exposed to DHT, researchers observed cell death in affected follicular cells.
The Scalp Paradox
If DHT is a “follicle killer,” why does it cause hair loss on the scalp while simultaneously stimulating thick, dark hair growth on the face (beard) and body?
This paradox suggests that the hormone itself is not the only variable.
Genetics: The Missing Piece
Simply stating that male pattern baldness is “hormonal” is not sufficient.
Can you determine how much DHT someone has based solely on their hair?
Do men in their 80s with a full head of hair lack testosterone altogether?
The answer is no.
The key factor is genetic sensitivity. Not everyone’s hair follicles respond to DHT in the same way. Male pattern baldness occurs when you have a genetic predisposition that makes your scalp hair follicles sensitive to DHT.
Genetics account for approximately 80% of the predisposition to androgenetic alopecia. It is a polygenic condition, meaning it is influenced by dozens of genetic variants rather than a single gene.
The X-chromosome myth
While one well-known risk gene is located on the X chromosome (inherited from the mother), researchers have identified over 60 genetic loci across multiple chromosomes that contribute to AGA. This means hair loss can be inherited from either parent.
In summary
Based on current knowledge, androgenetic alopecia is a hormone-driven condition that occurs in individuals with a genetic sensitivity to DHT in the scalp.
Secondary Factors to Consider
Blood flow
We know that areas of the scalp without hair have reduced blood flow, and we also know that adequate blood supply is necessary for hair growth. The question is:
Does reduced blood flow cause hair loss, or does hair loss lead to reduced blood flow?
Most evidence suggests the latter. However, for regrowth to occur, restoring circulation to the follicles is essential.
Inflammation
Around 40–50% of individuals with AGA show signs of scalp inflammation. This inflammation can have multiple causes, including microorganisms, prostaglandins, and histamine responses. Treatments such as ketoconazole (e.g., Nizoral) or cetirizine can help in some cases, though results vary.
Maintaining a healthy scalp environment will always support better hair growth.
Collagen
Collagen plays a role in both skin and hair health and naturally declines with age.
Lifestyle: Does It Matter?
Yes — and no.
If you have the genetic predisposition for AGA, lifestyle factors influence how fast you lose hair, not whether you lose it.
Studies on identical twins show that while both may eventually experience hair loss, the rate and severity can differ significantly due to:
-
Chronic stress: Elevated cortisol disrupts the hair cycle and increases inflammation
-
Diet and nutrition: Protein, iron, vitamin deficiencies, and habits such as smoking can weaken hair and accelerate shedding
-
Metabolic health: AGA has been linked to metabolic syndrome, high BMI, and insulin resistance, suggesting overall health impacts scalp function
So How Do We Address Hair Loss?
You cannot change your genetics. For individuals with AGA, the most effective approach is reducing DHT, ideally locally in the scalp.
At the same time, it is important not to actively worsen the situation by ignoring lifestyle factors. While lifestyle changes alone are unlikely to stop hair loss long-term, chronic inflammation and poor metabolic health will accelerate it.
For regrowth and maintenance, blood flow, circulation, and scalp health play important supporting roles.
For more information on how to slow, pause, or manage hair loss — through medical treatments, natural approaches, surgery, or hair systems — continue reading the related articles on this site.