Why your hair is shedding (and when it stops)

Around week six, it starts. A few extra strands in the shower. Then more. Then you're Googling "GLP-1 hair loss" at midnight wondering if you made a mistake.

You didn't.

What's happening is called telogen effluvium — a temporary shift in your hair growth cycle triggered by rapid weight loss or significant caloric reduction. Your body, in its infinite wisdom, decides that hair is a luxury it can defer. It's not permanent. But it is real, and it's worth understanding.

The ferritin connection is the part most doctors skip. Ferritin is your body's iron storage protein, and it's the single most underdiagnosed driver of hair shedding in women on GLP-1s. When you eat less, you absorb less iron. When ferritin drops below 40 ng/mL — even if your haemoglobin looks fine — your follicles start to struggle.

The catagen phase (the transition phase of hair growth) shortens. More hairs enter the resting phase simultaneously. Three months later, they fall out together.

What actually helps: get your ferritin tested, not just your iron. Supplement if you're below 70. Eat protein at every meal — your follicles are made of it. And give it time. Most people see regrowth between months four and six. Read more about the role of biotin and zinc in hair retention in our guide on hair loss on Mounjaro.

The shedding is not a sign that something is wrong. It's a sign that your body is adapting.

This article is informational and does not replace medical advice. When in doubt, consult your doctor.