UNderstanding hair cycles

Hair Life Cycle

Hair grows in a repeating cycle with four main phases, and each hair follicle moves

through these phases independently.

1. Anagen (Growth Phase)

• This is the active growth stage.

• Hair cells divide rapidly, producing new hair.

• Lasts 2–7 years (sometimes longer).

• About 85–90% of the hair on your scalp is in anagen at any time.

• The longer this phase lasts,

the longer and thicker hair can grow.

2. Catagen (Transition Phase)

• A short transition period where growth stops.

• The hair follicle shrinks and detaches from the blood supply.

• Lasts about 2–3 weeks.

• Only around 1–2% of hairs are in this phase.

3. Telogen (Resting Phase)

• The follicle is inactive,

but the hair remains in place.

• Lasts around 2–4 months.

• About 10–15% of scalp hairs are in telogen.

• At the end of this phase, the hair prepares to shed.

4. Exogen (Shedding Phase)

• The old hair is released and falls out.

• Occurs naturally as new hair begins to grow underneath.

• Shedding 50–100 hairs per day is normal.

Why this matters

• Hair thinning often occurs when more hairs enter telogen early or when the anagen phase shortens.

• Treatments like minoxidil, laser therapy, PRP, and transplants aim to extend anagen and reduce excessive shedding.

GLP side effects

IMPORTANT INFORMATION

Does GLP-1 (Ozempic) cause hair loss?

Good question — the link between GLP-1 receptor agonists (GLP-1 RAs) (like semaglutide, liraglutide, or tirzepatide) and hair loss has been increasingly discussed

as more people use these drugs for weight loss or diabetes.

Hair Loss Often Comes from Rapid Weight Loss

The most likely reason for hair shedding in people on GLP-1 drugs is telogen effluvium —

a temporary hair shedding that occurs when the body undergoes physiologic stress or nutrient shifts.

Rapid weight loss = metabolic stress → more hairs shift prematurely from the “growth” phase (anagen) to the “resting/shedding” phase (telogen).
This typically starts 2–3 months after the onset of rapid weight loss.

Nutrient Deficiencies Can Contribute

When calorie intake drops, or food choices narrow, you can become

deficient in nutrients important for hair growth:

Protein (keratin synthesis)

Iron

Zinc

Biotin

Vitamin D

B vitamins

Even if blood levels aren’t dramatically low, mild deficiency can contribute to shedding.

Hormonal and Metabolic Adjustments

Weight loss (especially fat loss) can alter:

Thyroid hormone levels

Sex hormone binding globulin (SHBG)

Estrogen/testosterone balance

These hormonal changes can influence hair growth cycles,

sometimes contributing to temporary shedding.

SO - YES! A LASER CAP CAN HELP !