Hair loss on keto is usually temporary shedding, not permanent baldness. The most common cause is telogen effluvium, a pause in the hair growth cycle that starts two to four months after a shock to the body, such as rapid weight loss, a big drop in calories, illness or stress. Keto itself doesn’t damage hair follicles, but eating too little protein, calories, iron or zinc while losing weight quickly can trigger it. In most people, hair grows back within six to twelve months once eating stabilizes. Eating enough protein and calories, losing weight more gradually, and checking iron levels help. If hair loss is patchy, lasts more than a few months or comes with other symptoms, see a doctor, as the NHS advises.
Why hair loss happens on keto
Rapid weight loss and low calories
Hair follicles cycle between growing (anagen), resting (telogen) and shedding phases. A sudden stress, including a big calorie deficit or fast weight loss, can push many follicles into the resting phase at once. About two to four months later, those hairs fall out together, so the shedding often shows up long after you started the diet. DermNet explains that telogen effluvium usually recovers on its own within months. This happens with any diet that causes fast weight loss, as well as after weight loss surgery, and it isn’t unique to keto.
Not enough protein
Hair is made mostly of a protein called keratin. Some people on keto eat lots of fat but not enough protein, worried that protein will stop ketosis. Most adults need at least 0.75 g of protein per kg of body weight a day, according to the British Nutrition Foundation, and more is useful during weight loss and in older age. Our guide to protein on keto explains how much to aim for.
Iron deficiency
Low iron is a known cause of hair shedding, and the NHS lists iron deficiency among the causes of hair loss. Women with periods are at higher risk, and keto cuts out fortified cereals and beans. Red meat, seafood, eggs, pumpkin seeds and leafy greens help. Our list of iron-rich foods has more.
Other nutrients
Zinc, selenium, vitamin D and biotin all play roles in hair health, but deficiency is uncommon in people eating a varied diet. Strict keto diets low in vegetables, nuts and seeds can fall short on some minerals. Our guide to nutrient deficiencies on keto explains what to watch.
Stress and illness
Keto flu, poor sleep, stress and illness can all add to the shock that triggers shedding.
What helps
- Eat enough. Avoid very large calorie deficits. Losing about 0.5 to 1 kg a week is gentler on the body than crash dieting.
- Get enough protein at every meal: eggs, fish, chicken, meat, Greek yogurt, cheese or tofu.
- Eat iron- and zinc-rich foods, such as red meat, shellfish, eggs, pumpkin seeds and spinach.
- Include plenty of non-starchy vegetables, nuts and seeds for vitamins and minerals.
- Ask your doctor about blood tests if shedding continues, including iron stores (ferritin), thyroid function and vitamin D. Our guide to keto blood tests lists them.
- Be gentle with your hair: avoid tight hairstyles, harsh treatments and very hot styling while it recovers.
- Be patient. New growth takes months to show.
Should you take biotin or hair supplements?
Biotin is often sold for hair growth, but there’s little evidence it helps unless you’re deficient, which is rare. High-dose biotin can also interfere with some blood tests, including thyroid and heart tests, so tell your doctor if you take it. Getting nutrients from food is the safer first step. If a blood test shows you’re low in iron or vitamin D, your doctor can recommend the right supplement and dose.
When it’s not keto
Not all hair loss on keto is caused by the diet. Other causes include:
- Male and female pattern hair loss, which is genetic and gradual.
- Thyroid problems, both overactive and underactive.
- Hormonal changes after pregnancy, around the menopause or with PCOS.
- Alopecia areata, which causes patchy hair loss.
- Some medicines.
The NHS advises seeing a GP if you have sudden hair loss, bald patches, hair loss with itching or burning, or if you’re worried about it.
How long until hair grows back?
Telogen effluvium usually stops within about six months of the trigger, and regrowth becomes noticeable over the following months. It can take a year for hair to return to its usual thickness. If shedding continues beyond six months, see a doctor to look for other causes.
Preventing hair loss when starting keto
- Start with a moderate deficit, rather than cutting calories very low.
- Plan protein first when building meals.
- Keep vegetables in every meal for vitamins and minerals.
- Don’t combine keto with intense new exercise and very low calories at the same time.
- Consider a less strict low-carb diet if you find it hard to eat enough on keto.
Our guide to keto side effects covers other early changes.
Common questions
Does keto cause permanent hair loss?
No. The shedding linked with diets is usually temporary and grows back. Permanent hair loss has other causes, such as genetics.
When does keto hair loss start?
Usually two to four months after starting, because of the delay in the hair growth cycle.
Will stopping keto stop the hair loss?
Not immediately. Shedding that has already been triggered will continue for a while. Eating enough and staying steady matters more than whether you stay on keto.
Can keto help hair grow back?
Not directly. Hair regrowth depends on resolving the trigger, such as eating enough after a period of rapid weight loss, correcting low iron, or treating a thyroid problem. A well-planned diet with enough protein, vitamins and minerals supports normal growth, whether or not it’s keto.
Safety note: Keto isn’t suitable for everyone. If you have diabetes, kidney or liver disease, take regular medication, or are pregnant or breastfeeding, talk to your doctor before cutting carbs this far (why it matters).
This article is general information, not medical advice. Talk to your doctor or a registered dietitian before making big changes to how you eat, especially if you have a health condition, take regular medication, or are pregnant or breastfeeding.
