Weight Loss & Hair Loss: Why Does it Happen?

With the rising popularity of weight loss medications like Ozempic®, Wegovy® and Mounjaro®, some patients are noticing an unpleasant side effect—hair loss. The truth is that hair loss can happen even if you’re losing weight without the help of a GLP-1 or weight loss surgery. Sudden changes in weight and body composition can trigger metabolic and hormonal changes in the body that can affect hair follicles and hair growth. Let’s take a closer look at the relationship between weight loss and hair loss and what to do if you’re noticing increased shedding while trying to lose weight.

What is drug-induced hair loss and why does it happen during weight loss?

Actually, drug-induced and weight-related hair loss could be classified as two different subtypes of stress-induced hair loss, or telogen effluvium (TE). How your body reacts to a drug is one type of stressor, whereas losing weight, which can happen with or without the help of weight loss medication, is its own potential trigger.

TE, or stress-induced hair loss, usually starts a few months after being exposed to a trigger. This type of hair loss is typically diffuse, meaning it affects the entire scalp as opposed to a specific area or areas, as in the case of pattern hair loss. Many cases of TE resolve on their own after a few months (between 3-6) without the need for intervention—usually this is when the source of stress is removed, and the hair follicles resume their usual growth cycle.

Hair loss after taking a GLP-1 such as Ozempic®, Wegovy®, or a GLP-1/GIP like Mounjaro®, is often related to dramatic weight loss. This can be due to several factors, including imbalances in caloric or nutritional needs, especially because GLP-1s can affect appetite, and metabolic shifts that happen because of changing body composition. These factors can result in biochemical changes that influence the hair growth cycle and cause active growth to stall.

On the subject of drug-induced TE, GLP-1s are not believed to be toxic to hair follicles. This means the drugs themselves less likely to be a direct cause of hair loss.

Does Ozempic® cause hair loss or is it from rapid weight loss?

Available clinical data suggests that Ozempic® doesn’t directly cause hair loss, and that hair loss is an indirect effect of how much weight you’re losing and how quickly.

For example, one study found that hair loss could be triggered by a weight loss percentage of approximately 15.21% at a rate of 3.54 kg/month. Interestingly, the study also noted that women and older adults were more likely to experience weight loss related TE, even if the amount of weight loss was less than men and younger adults (Kang et al., 2024).

Can Wegovy® trigger hair loss and how common is it?

Hair loss has been reported as a possible side effect of Wegovy, although its frequency isn’t well defined. The official drug monograph for Wegovy® (generic semaglutide) states that severity of hair loss is connected to the amount of body weight reduction. 5.3% of hair loss cases were associated with a >20% reduction in body weight, compared to 2.5% in cases where patients lost less than 20% of their body weight. Overall, hair loss as a side effect was reported in 3% of adults using Wegovy and 1% of placebo users, making this an uncommon side effect (Wegovy®, Novo Nordisk).

The actual mechanisms behind why weight loss triggers hair loss are not well understood, possible causes include malnutrition, vitamin deficiencies, and hormonal changes (Haykal, 2025; Nakhla et al., 2024).

Does tirzepatide (Mounjaro®/Zepbound®) lead to hair loss?

Currently, there isn’t conclusive data to support whether some GLP-1s are more likely to cause hair loss than others, but according to one review, semaglutide and tirzepatide have the strongest associations with hair loss (Branyiczky et al., 2025).

We do know that dramatic weight loss associated with taking these types of medications can induce TE. Some early data that suggests that this risk is not necessarily equal amongst men and women, and that women may be more likely to experience TE due to weight loss compared to men.

Interestingly, some patients have reported seeing the opposite effect, hair regrowth, while taking tirzepatide. The exact mechanisms are still being researched, but positive effects on hair growth could be due to hormonal changes because of losing weight, such as improved insulin sensitivity. Insulin has previously been shown to play a role in certain types of hair loss, such as androgenetic alopecia (pattern hair loss).

Why does losing weight itself cause hair thinning or shedding?

While weight loss induced TE hasn’t been studied in large-scale clinical trials, there have been many case studies examining the relationship between sudden weight reduction and hair thinning.

One theory behind why TE occurs has to do with calorie restriction. To lose weight, it’s necessary to be in a caloric deficit. Some experts believe that this restriction can affect rapidly-growing cells of the hair follicles by reducing the supply of nutrients and ultimately causing the growth cycle to transition out of the active growth phase, and into the resting phase. Hormonal shifts, including possible changes in thyroid hormone levels after using GLP-1s, have also been linked to hair loss (Haykal, 2025).

The good news is that the same studies also show that once normal caloric intake resumes and weight loss reaches the maintenance stage, hair growth also normalizes (Kang et al., 2024).

Is hair loss from GLP-1 medications or weight loss temporary or permanent?

Hair loss associated with GLP-1 use is not typically permanent. In many cases, this type of stress-related hair loss resolves within 3-6 months following stabilization of weight loss and balanced caloric intake.

If you notice hair loss worsening over time, we recommend reaching out to a healthcare professional to rule out any other possible causes (e.g., pattern hair loss, hair loss relating to thyroid issues or other underlying medical conditions).

How long does hair loss from Ozempic®, Wegovy®, Mounjaro®, or weight loss last?

Hair loss associated with using Ozempic®, Wegovy® or Mounjaro® usually resolves once weight loss slows down or stabilizes, and your body's nutritional needs are met. The timeline varies from person to person, but this kind of stress-related hair loss typically improves after 3-6 months.

There are some factors that can extend this recovery period. Examples include continued rapid weight loss, malnutrition, or situations that subject the body to additional stress (for example, illness, adding or starting a new medication, excessive exercise).

How to stop or reduce hair loss while losing weight or taking GLP-1s

Some of the best things you can do to reduce the severity of hair loss when undergoing major weight loss include:

1. Staying on top of of your nutritional needs
2. Minimizing other possible sources of stress and
3. Closely monitoring progress with your doctor to ensure that weight loss is happening safely and sustainably.

One of the main potential causes of shedding associated with weight loss is a lowered caloric intake and not getting enough of certain nutrients and minerals such as iron, zinc, vitamin D, and B complex vitamins. If you are losing weight with the help of a GLP-1, you may want to talk to your doctor about whether adding a multivitamin or supplement might be beneficial, in addition to working with a nutritionist.

Stress management can also help with TE. Stress hormones like cortisol can be hard on the body and especially hair follicles, which are sensitive to hormonal fluctuations. If you're prone to stress, finding strategies that work for you, such as maintaining a regular sleep schedule, seeking professional help with mental health, or keeping up with exercise are all ways to keep stress levels low.

Finally, if you’re on a GLP-1, chances are you’re already checking in with a doctor regularly to make sure that you’re on track to meet your weight loss goals. Since the severity of hair loss seems to be connected to how much weight you’re losing and how quickly, if this becomes a concern, you may want to talk to your doctor about titrating your medication to lower your risk for shedding.

What vitamins, nutrients and diet changes help prevent hair loss during weight loss?

Hair loss while trying to lose weight is more likely due to overall reduced caloric intake than a deficiency in any specific nutrient or micronutrient. The average North American diet makes it relatively easy to obtain all these nutrients, and true clinical deficiencies in the general population are uncommon. Additionally, it’s a matter of debate whether certain nutrients or micronutrients are more important than others when it comes to hair growth.

Having said that iron, zinc, vitamin D, and B complex vitamins such as biotin do appear to play roles in the hair growth cycle and hair health. As part of your weight loss plan, you may want to work with a nutritionist who can help design a meal plan that includes foods that are rich in these nutrients.

Best supplements and topical treatments for weight-loss related hair loss

Hair loss associated with weight loss doesn’t typically require any intervention, and it's unclear whether supplements or topical treatments (specifically, non-medicated ones) would be beneficial for this type of temporary hair loss.

Topical minoxidil, or Rogaine® has the strongest evidence of all your over-the-counter options for promoting hair growth but remember that minoxidil takes time to work (usually around 3-6 months).  If you’re experiencing typical TE, this is usually when you start to see improvements in shedding. Minoxidil may still be helpful for boosting hair density if you were already struggling with thinning prior to weight loss, but it’s not a short-term fix.

Natural supplements, including those containing popular hair loss ingredients like saw palmetto extract could help, but saw palmetto specifically targets DHT—the cause of pattern hair loss, not TE. It’s unclear whether saw palmetto would be helpful for weight loss induced TE. There is some soft evidence that supplements containing collagen could be helpful for hair growth, but bear in mind that collagen taken orally needs to be broken down by the body into smaller peptides before they can do anything.

If you are considering taking a supplement while on a GLP-1, make sure to discuss this with your doctor to make sure that you can do this safely.

Can stress, nutrient deficiency, or hormones make hair loss worse during weight loss?

Yes, stress, changes in your diet and hormones can influence hair loss while you’re trying to lose weight. In some cases, having an underlying health condition such as thyroid dysfunction (hypo or hyperthyroidism), PCOS or diabetes, could also contribute to hair loss.

Additionally, it’s possible that you may be dealing with pattern hair loss or another more specific hair loss disorder. If thinning is worsening as opposed to getting better as your weight stabilizes, it’s important to talk to your doctor about this to rule out any underlying causes and get the right treatment, if needed.

Practical lifestyle tips to slow shedding while continuing weight-loss treatments

Here are some practical tips that can help keep shedding in check while using a GLP-1 or other weight loss aids:

• Eating a balanced diet with enough calories
• Managing stress, including getting enough sleep
• Regular check-ins with doctors to ensure weight loss is sustainable and happening at a safe rate
• Being aware of any other medical conditions that could be affecting hair health
• Taking care of your scalp and prioritizing scalp care (cutting back on chemical and/or heat styling, opting for hairstyles that avoid putting extra tension on hair, keeping the scalp clean and hydrated)
  

When to see a dermatologist or doctor about weight-loss related hair loss

It’s important to talk to your doctor or consider seeing a dermatologist if your hair loss is worsening over time. There are many health conditions and hair loss disorders that could be behind it, and some of these may require additional diagnostics (for example, blood tests) or specialized examinations. Additionally, if you start to notice hair loss in other parts of the body, for example, your eyebrows or eyelashes, this could also be an indicator of an underlying condition.

Bottom line: Weight loss and hair loss

Hair loss is a well-known potential side effect of weight loss, particularly if weight loss is significant over a short period of time. This type of hair loss is most likely a form of telogen effluvium (TE), or stress-induced hair loss. Possible causes include reduced caloric intake or less commonly, malnutrition or nutrient deficiencies, which can affect the fast-growing cells found within hair follicles, as well as possible metabolic or hormonal changes associated with changes in body composition. TE related to weight loss typically resolves in 3-6 months without the need for additional treatment or intervention as weight loss stabilizes.

Strategies that can help mitigate hair loss during this time include working with a nutritionist to ensure that caloric and nutritional needs are met, managing stress, monitoring weight loss progress with your doctor and prioritizing your scalp and hair care routine so that you’re taking the best care possible of the hair that you have.

If you notice increased thinning, or hair loss doesn’t improve over time, we recommend consulting with your doctor to help rule out any underlying health conditions or hair loss disorders. Losing weight can be a powerful first step to regaining control over your health, and it doesn’t need to happen at the cost of your hair or self-esteem.

References:

Alsuwailem, O. A., Alanazi, R., Almutairi, H. M., Asiree, R. H., Almutairi, W., Almutairi, T. M., Zamandar, A., & Alkhames, S. (2025). Hair loss associated with glucagon-like peptide-1 (GLP-1) receptor agonist use: A systematic review. Cureus, 17(9), e92454. https://doi.org/10.7759/cureus.92454

Branyiczky, M. K., Lowe, M. S., McMullen, E., Donovan, J., & Touraj Khosravi‐Hafshejani. (2025). Effects of GLP ‐1 receptor agonists on hair loss and regrowth: A systematic review. International Journal of Dermatology. https://doi.org/10.1111/ijd.70133

Haykal D. (2025). Alopecia and semaglutide: Connecting the dots for patient safety. Journal of Cosmetic Dermatology, 24(3), e70125. https://doi.org/10.1111/jocd.70125

Kang, D. H., Kwon, S. H., Sim, W. Y., & Lew, B. L. (2024). Telogen Effluvium Associated With Weight Loss: A single center retrospective study. Annals of Dermatology, 36(6), 384–388. https://doi.org/10.5021/ad.24.043

Nakhla, M., Nair, A., Balani, P., Ujjawal, A., Arun Kumar, P., Dasari, M., Yukselen, Z., Bansal, K., Ganatra, S., & Dani, S. S. (2024). Risk of suicide, hair loss, and aspiration with GLP1-receptor agonists and other diabetic agents: A real-world pharmacovigilance study. Cardiovascular Drugs and Therapy. https://doi.org/10.1007/s10557-024-07613-w

Wegovy ® Product Monograph. Novo Nordisk.  [Feb 2024]. Available from: https://www.novonordisk.ca/content/dam/nncorp/ca/en/products/Wegovy-product-monograph.pdf