Hair thinning: why it happens and what helps

Rapid weight loss can trigger temporary hair shedding — this is not unique to GLP-1, and it's not permanent.

What it is

Telogen effluvium: a stress response where hair shifts from growth phase to shed phase. Triggers include major weight loss, illness, or hormonal change. Onset 3–4 months after the trigger.

Why it happens on GLP-1

Rapid weight loss = body interpretation of stress. Lower calorie intake can also mean lower protein, lower iron, lower B12. Each of those, on their own, can drive hair loss.

What helps

Hit your protein target (1.4 g/kg). Check iron + ferritin + B12 — supplement if low. Don't change shampoo, don't panic. Hair regrowth begins 3–6 months later as your body re-equilibrates.

When to investigate further

If shedding lasts more than 9 months, or hair is patchy not diffuse, ask for a dermatology referral. There may be an unrelated cause.