Hair loss after weight-loss surgery: why it happens

Weight-loss surgery, also called bariatric or metabolic surgery, can bring big health benefits. But many people are surprised when, a few months after the operation, their hair starts to come out in larger amounts than usual. Knowing why this happens, and that it often improves, can make it less frightening.

How common is it?

A 2021 systematic review and meta-analysis pooled 18 studies with 2,538 people who had weight-loss surgery ¹. It found:

• About 57% of people reported hair loss after surgery (the range across studies was wide, from 42% to 71%) ¹.
• Hair loss was reported less often in studies with longer follow-up, which fits with it being temporary for many people ¹.
• It was more common in younger people and in women ¹.

The authors said larger, forward-looking studies are still needed ¹.

Why it happens

The most likely explanation is telogen effluvium, a type of shedding that happens when a major stress on the body pushes many growing hairs into the resting phase at the same time. The hairs then fall out a few months later ².

Several recognised triggers of telogen effluvium can occur around weight-loss surgery ²:

• Major surgery itself.
• Rapid weight loss and very low calorie intake, similar to crash dieting.
• Low protein intake, which is common in the early weeks when meals are very small.
• Iron deficiency.

Because hair growth runs in cycles, the shedding usually shows up some weeks to months after the operation, not straight away.

The nutrient link

The meta-analysis also looked at blood levels of nutrients. People with hair loss after surgery tended to have lower levels of zinc, folic acid and ferritin (a measure of iron stores) ¹. Blood levels of iron and vitamin B12 were not linked with hair loss in the pooled results ¹.

This does not prove that low nutrients caused the hair loss, but it shows why keeping up with nutrition after surgery matters.

What the NHS advises after surgery

The NHS explains that after weight-loss surgery you will need to change the way you eat and drink, including eating slowly, chewing carefully, eating small amounts at a time and taking vitamin and mineral supplements ³. You will also be given a diet plan that moves gradually from fluids to runny food, soft food and then normal food over the first weeks ³.

The NHS adds that you will need regular follow-up for the rest of your life, which may include blood tests to check your vitamin and mineral levels ³.

Practical steps to support your hair

• Take the supplements you are prescribed. Do not skip them, and do not swap them for a hair supplement without asking your surgical team or dietitian.
• Prioritise protein. Follow your diet plan's protein advice, especially in the early months. See protein and hair.
• Go to your follow-up appointments. Blood tests can pick up low iron, zinc, folic acid and other nutrients. See blood tests for hair loss and zinc and hair loss.
• Avoid high-dose supplements on your own. More is not always better, and some nutrients can be harmful in excess. Ask your team before adding anything.
• Be gentle with your hair. Use a mild shampoo, avoid tight styles and limit heat and chemical treatments while hair is shedding.
• Track changes with photos so you can see improvement over months.

What to expect

For many people, shedding after weight-loss surgery is temporary. The finding that hair loss was less common with longer follow-up supports this ¹. Once weight stabilises and nutrition is steady, hair often starts to recover, although it can take several months for fullness to return because hair grows slowly.

When to ask for help

Contact your surgical team or doctor if:

• shedding continues well beyond the first months after surgery, or gets worse
• you notice bald patches, a widening parting or scalp redness or pain
• you also feel very tired, short of breath, dizzy or notice brittle nails, which may suggest a nutrient deficiency
• you are struggling to eat enough or keep food down

Ongoing shedding may have another cause, such as pattern hair loss, a thyroid problem or a medicine. See chronic telogen effluvium. If you are using weight-loss medicines rather than surgery, see diabetes, weight-loss medicines and hair loss. For general first steps, see what to do when you first notice hair loss.

Frequently asked questions

How common is hair loss after bariatric surgery?

A meta-analysis of 18 studies found about 57% of people reported hair loss after surgery ¹.

Does hair loss after weight-loss surgery last?

Usually not. It was reported less often with longer follow-up, which fits with temporary shedding ¹.

Which nutrients are linked with it?

Lower zinc, folic acid and ferritin were associated with hair loss after surgery; iron and vitamin B12 levels were not ¹.

Do I need supplements after weight-loss surgery?

Yes. The NHS says you will need to take vitamin and mineral supplements and have regular blood tests ³.

Educational content. Not medical advice.