It has long been known that sudden, crash diet weight loss can cause hair loss [1]. But what about safer, healthier dietary patterns? While some beauty influencers warn about intermittent fasting-induced hair loss, others point out that it may actually promote hair growth. So let’s take a look at what science reveals.
The bad news is that certain forms of intermittent fasting can indeed make your hair fall out. The good news is, however, that this type of hair shedding is temporary and most people can expect regrowth to resume within 3-6 months [2]. Find out all about the mechanisms that cause hair loss when intermittent fasting, as well as the best ways to prevent and shorten this condition.
This article will tell you everything you need to know about the complex relationship between intermittent fasting and hair loss. It will explain how different aspects of fasting can disrupt your hair growth cycle, and offer helpful suggestions for how to reduce the likelihood of that happening. We will help you determine whether you are among those at risk of developing hair shedding while intermittent fasting and reveal the dietary patterns most prone to affecting your hair. Finally, we will equip you with the right information to discern whether the fasting is really at fault for your hair loss, or whether you may be experiencing an entirely different type of alopecia.
Key takeaways
Intermittent fasting is an umbrella term that describes eating patterns involving specific time windows where food intake is allowed, followed by periods of food abstinence. Usually, with safely performed intermittent fasting, a variety of food groups are allowed, and caloric intake is not severely restricted during the feeding window. However, during the fasting periods, caloric intake is very low or fully absent [3]. Water and other very low-calorie beverages (e.g. black coffee, unsweetened tea) are generally allowed at any time to reduce hunger, provide energy and maintain hydration.
People engage in intermittent fasting for a variety of reasons, from trying to lose weight to improving their overall health or observing religious practices. Depending on purpose and personal preference, people normally use one of several popular dietary patterns.
Here are some of the most common types of intermittent fasting that people around the world engage in [4][5][6]:
There are good arguments both for and against intermittent fasting when it comes to health considerations. The greatest disadvantage is that long and restrictive fasting periods can place you at risk of malnutrition or illness, especially if you have certain medical conditions (e.g. diabetes, digestive problems, a weak immune system, etc.) [3]. Some forms of intermittent fasting, such as prolonged water fasts, 20:4 time-restricted fasting over long periods or full-time OMAD diets, can deprive you of nutrients and/or overload your digestive system with large meals eaten over a short period.
People who are trying to lose weight sometimes drastically reduce caloric intake and/or restrict certain “bad” food groups (e.g. carbs, sugar, fat) for the meals they have during the eating window. Combined with prolonged fasting, this can deprive your body of the vitamins, minerals and proteins it needs, potentially leading to low energy levels and nutrient deficiencies. In the long run, this can be very harmful to your health.
However, when done safely (preferably under a nutritionist’s guidance), there are also recognised health benefits associated with short-term intermittent fasting (there is insufficient research data to assess its long-term impact) [6][8][5][3]:
The health outcomes experienced by each individual as a result of intermittent fasting depend on a variety of factors, such as their previous diet, their fasting type and duration, their overall health condition, their metabolic particularities, their compliance and result expectations, etc.
Yes, under certain circumstances, intermittent fasting can cause hair loss in some people. This is because it can trigger a type of alopecia called telogen effluvium. This temporary condition occurs following a disruption to your hair growth cycle, which interrupts your hair follicles’ growth (anagen) phase, pushing an excessive proportion of them into the resting (telogen) and eventually, the shedding (exogen) phase.
Telogen effluvium is often triggered by physical and/or psychological stress (e.g. illness, surgery, a stressful life event, etc.) or develops when your body doesn’t have enough resources to produce healthy hair. Fortunately, it normally resolves itself within a few months after the triggering factor has ended.
Examples of patients experiencing diffuse hair loss from telogen effluvium.
Image credit: Wiley Online Library
Telogen effluvium manifests with a single major symptom: diffuse hair loss all over the scalp. It can make up to 50% of your hair fall out in clumps, over a rather short period of time [9]. However, while your hair may become so thin that you can see your scalp, it will not normally cause bald spots or patterned hair loss.
Some of the patients with telogen effluvium sometimes also experience a mild burning sensation on the scalp (known as trichodynia). However, it isn’t normally accompanied by other scalp symptoms, such as redness, inflammation or a rash.
Depending on the type of intermittent fasting you choose and your diet during the feeding window, telogen effluvium may typically develop due to one or more of the following causes:
If you are eating too few calories during your feeding window and fasting for extended periods, you may suddenly lose a large amount of weight. This can shock your body into thinking resources are scarce, triggering telogen effluvium. Or, if your diet is very restrictive, you may actually be producing insufficient energy to allow for healthy hair growth. One study reveals that suddenly losing 15% of your body mass or over 3,5/month places you at risk of developing hair shedding [31].
Most commonly associated with: excessively calorie-restrictive alternate-day fasting, prolonged or frequent water/juice fasting
Human hair needs a variety of nutrients to grow, and certain mineral and vitamin deficiencies can cause hair loss. This often happens when you are excluding certain food groups from your diet during intermittent fasting (this is also one of the main ways the keto diet can cause hair loss). Doing so in the long term can deprive you of some of the nutrients you need to grow healthy hair, such as [10][11] :
When you have a clinical deficiency of some of these micronutrients (especially iron, which can lead to anaemia-induced hair loss, or vitamin D), you may develop the diffuse hair shedding typical of telogen effluvium, alongside other health issues.
Normally, your hair should grow back with nutrient supplementation, but research shows that in rare cases, this may only happen partially or may not happen at all [10]. Moreover, if your nutritional deficiency goes undetected and/or untreated for prolonged periods or is combined with other stressors, you can develop chronic telogen effluvium, which can last for up to 10 years [12]. So it is best to monitor your nutrient levels and intake during intermittent fasting.
Most commonly associated with: prolonged partial fasting (e.g. long religious fasts), prolonged or frequent water/juice fasting
A growing body of research [15][16][17][18] shows that even when undergone correctly, common types of intermittent fasting can lead to hair follicle stem cell death, impairing the follicles’ ability to regenerate. This happens because the disrupted feeding cycle causes the adrenal glands to produce stress hormones, which negatively affect the dermal papilla, the part of your hair anatomy which sends growth signals to the stem cells in the hair bulb. This causes the shafts to stop growing and prematurely enter their shedding (telogen) phase.
Most commonly associated with: prolonged time-restricted eating or alternate-day fasting
Being on a new diet can be psychologically and physically stressful, especially when it involves living an active lifestyle, but going long stretches of time without eating. During the first few weeks of intermittent fasting, your body can become confused regarding food availability. At the same time, you may be extra anxious, tense or irritable due to hunger. This stress alone can be enough to trigger telogen effluvium in some people, especially if they exercise or do heavy physical labour or if they were already going through a stressful period [9].
Most commonly associated with: Eat-stop-eat fasting, prolonged or frequent water/juice fasting
While more research is needed to determine the benefits of intermittent fasting for hair growth and hair health, it may have the following positive effects:
If you are in at least one of the following categories, you may be at higher risk of developing telogen effluvium during intermittent fasting:
Before it starts to fall out, some people notice discreet changes in their hair quality, such as developing dry, brittle hair that breaks off easily. Flatness, dullness, and a rougher texture can also be tell-tale signs that your hair is not getting all the nutrients it needs. So if you start to notice that your hair feels like straw and that it is losing its bounce and vibrancy, you may need to monitor and, if needed, adjust your diet plan.
Moreover, in many cases, hair shedding is not the only sign that your intermittent fasting regimen may be depriving your body of the necessary nutrients. People who are not getting all the nutrition they need from their diet may also experience other symptoms, such as [23]:
If you experience such symptoms, especially alongside diffuse hair shedding, it is best to see your GP. They may order blood tests to reveal any nutritional deficiencies.
There is no sure-fire method to prevent intermittent fasting – induced hair shedding. Sometimes, your body will simply overreact to the changes in your diet. However, following this advice will substantially decrease your risk of developing telogen effluvium:
A nutrition specialist will get a detailed account of your health history, your current and previous diets and your goals in terms of intermittent fasting. They may also order blood tests to get a better idea of your nutritional needs. Then, they will work with you to determine the most sustainable type of fasting for your body, which can also bring you closest to your goals and make compliance easiest for you. Following a personalised diet will keep you safest from all health harms, hair loss included.
If this is an option for you, start with a more permissive type of intermittent fasting and then, if needed, work your way to more restrictive ones. For example, you can gradually increase the time between meals until you reach your fasting goal. Or, if you choose a partial fast, you may want to remove the restricted foods from your diet one by one, instead of all at once. This decreases the shock to your body and makes accommodation to the new dietary pattern easier.
An average, healthy person needs to eat approximately 1400 (for women) – 1900 (for men) calories to maintain their levels of energy [14]. Certain factors can modify this figure, such as a person’s height and weight, their health condition, their level of physical activity or their environment. However, research shows that consuming fewer than 1000 calories per day in the long term can lead to hair loss, alongside other health problems [1].
If you are intermittent fasting to lose weight, reducing your normal daily calorie intake by 500-600 is normally sufficient to obtain sustainable slimming [14]. However, crash dieting, such as eating very few calories during the feeding window, can make you sick in the long term and it will very likely make your hair fall out as well until you revert to a more balanced diet [1].
Calorie intake is not the only thing you need to worry about when intermittent fasting. You also need to make sure you are getting all the nutrients your hair needs to grow healthy. This is not normally a problem if you eat a varied diet during the feeding window. However, if you are on a partial diet for a long time, restricting entire food groups, you can develop nutritional imbalances.
Certain nutrients are sourced predominantly from certain kinds of food (e.g. many people get most of their iron from meat). Cutting out those foods means you need to find alternatives to replace them (e.g. getting your iron from increased leafy green consumption, and, if needed, iron supplements).
Finding ways to relax and decompress during your fasting periods can help your mind, body and hair. Taking long walks in nature or exercising can release feel-good hormones. Creative hobbies or gaming can also keep your mind off your diet and give you a chance to unwind. As can spending quality time with your loved ones. Being psychologically relaxed won’t automatically prevent telogen effluvium, but being under significant stress can increase your chances of developing this condition during your intermittent fasting.
The best essential oils for hair growth (e.g. rosemary oil for hair) can keep your locks nourished, moisturised and healthy. At the same time, they have individual properties that can help reduce certain types of hair loss and stimulate hair growth. Black seed oil for hair growth is the most helpful in preventing and reducing telogen effluvium (to be discussed). However, rosemary oil has been found to be as effective as topical Minoxidil 2% in reducing androgenetic alopecia by improving blood flow to your hair follicles [24]. This can also help stimulate hair growth during intermittent fasting.
Hair growth supplements (e.g. biotin for hair growth) are a flourishing market. However, they are only necessary and effective if you are experiencing a nutritional deficiency. If you are aware that you already have clinically low levels of a vitamin or mineral needed for hair growth, supplementing it may be a good idea while you are fasting. However, you should know that food is always the best source of nutrients.
Normally, telogen effluvium resolves itself without any treatment once the stressor that has triggered it has been removed. So in most cases, if you are undergoing a well-balanced and safe dietary pattern, all you need to do is wait 3-6 months for your hair to start growing back.
However, if this does not happen, you need to understand the exact cause of your hair shedding: are you eating too few calories? Have you developed a nutritional deficiency? Are you simply under constant stress? Is your hair loss truly related to your diet at all? A trichologist can help you get the right answers to these questions
In rare cases, telogen effluvium can become chronic and last for over 6 months (up to a decade). In this case, you may need to get some hair growth treatment to help reverse it. Here are some scientifically proven options, which can also help speed up your recovery from regular telogen effluvium:
This highly versatile hair loss medication has been proven to shorten the duration of telogen effluvium, helping your hair to return to its growth phase [25]. Moreover, it can also treat other conditions, such as androgenetic alopecia and alopecia areata, so if you are experiencing other concurrent types of hair loss, it can help improve their symptoms as well. Minoxidil works by dilating the small blood vessels in your scalp, so a greater amount of oxygen and nutrients can reach your hair follicles.
This treatment is also known as red light therapy for hair growth, because, as the name reveals, it uses red (or near-infrared) light to stimulate your hair follicles for growth [26]. The light gets absorbed into your scalp, where it improves blood flow and optimises the activity of your cell mitochondria. This can help push your follicles back into the growth stage sooner.
PRP hair treatment can help improve the symptoms of most types of alopecia, including chronic telogen effluvium [27]. That is because the platelet-rich plasma, harvested from a small sample of your own blood, contains an abundance of growth factors which help hair follicles repair and restore the small blood vessels around them.
If you prefer an inexpensive herbal remedy for your intermittent fasting-induced hair shedding, you can always try some black seed oil. Research shows that with regular application, it can help regulate your hair cycle and shorten the duration of telogen effluvium [28].
Sometimes, your hair loss may start around the same time as your intermittent fasting, coincidentally, without being related to it. The most obvious symptoms that this may be the case are as follows:
Several types of alopecia can cause hair shedding or hair loss. Here are some of the most common and how to recognise them:
In men:
In women:
In both genders:
If your hair loss is not caused by intermittent fasting, it’s best to know as early as possible. That is because androgenetic alopecia – the most widespread hair loss condition – can progress if left untreated. See a trichologist to diagnose your hair shedding if it does not improve within 6 months of onset and/or if it is accompanied by other scalp symptoms than diffuse hair thinning.
Normally, telogen effluvium resolves within 3-6 months of the triggering event [2]. However, that implies that the stressor has been removed (e.g. if you had a nutritional deficiency, it has been corrected). Otherwise, this condition can continue until your hair has the right conditions to grow healthy once more. In rare cases, prolonged telogen effluvium can become chronic and last from a few years to as long as a decade.
Fasting is a practice widely associated with religious observance and it is an important aspect of many major faiths. In the UK, the main types of religious intermittent fasting are associated with Christian and Islamic faiths. Here is how fasting can affect your hair health in each of these religions:
Typically, observant Christians are recommended to fast each week on Wednesdays and Fridays, as well as hold longer fasts (around 40 days around major religious holidays, especially Christmas and Easter). Christian fasting generally involves abstaining from common animal-sourced products (e.g. meat, eggs, dairy). This is a partial intermittent fast, as they are allowed to eat at any time of the day and in any quantities, as long as they only consume the permitted food types.
Christian fasting is normally mild on your hair and overall health, as it does not involve severe food restrictions. However, fasting for 40 days can lead to nutritional insufficiencies or deficiencies if you don’t replace the nutrients you used to get from animal-sourced products.
How to make your Christian fast more hair-friendly: Make sure you are getting all the nutrients you need during long periods of fasting. Iron, Calcium and Vitamin D are the most problematic, as many people get most of their daily recommended dose from meat, respectively eggs and dairy. However, increasing your leafy greens or fortified cereal consumption can reduce the risk of developing a deficiency.
The main fasting period in the Islamic faith is the Ramadan fast (known as Sawm). It typically lasts a month, and observant Muslims are recommended to refrain from any food or drink from dawn until sunset. This is a form of periodic fasting, as it does not restrict any food groups, but it creates a 12-16-hour fasting period followed by a feeding window between sundown and sunrise.
Moreover, aside from the Sawm, some Muslims voluntarily fast Mondays and Thursdays, on the White Days (13th, 14th and 15th of each month), any 6 days of the month of Shawwal, etc. This is also a periodic fast that is observed during the hours of daylight.
Periodic fasts are less likely to cause nutritional deficiencies, as you eat all normal food groups, in sufficient portions. However, during extended fasts, the body can still be shocked by the sudden change in dietary habits, or your hair follicle stem cells could be damaged, triggering hair loss [30].
How to make your Islamic fast more hair-friendly: Start gradually spacing out your meals increasingly far apart in the weeks leading up to Ramadan. Or at least cut out snacking between meals. This will slowly ease your body into intermittent fasting, reducing the stress of suddenly changing your dietary patterns.
If you want to know more about the most hair-friendly diets or are experiencing hair loss while intermittent fasting, our experts at the award-winning Wimpole Clinic are here to help. All you need to do is book a consultation with one of our experienced hair specialists at your most convenient clinic location.
Our doctors will get a full account of your health and diet history, order any necessary hair loss blood tests and use their state-of-the-art diagnostic trichology tests to get to the root of your hair problems. They will be happy to answer all of your questions and help you find the most hair-friendly options for your intermittent fasting needs.
Do you want to find out even more about the relationship between intermittent fasting and hair loss? You may find the information you are looking for among the answers to these frequently asked questions:
The worst types of intermittent fasting for your hair are the more radical ones, which limit calorie and nutrient intake for extended periods. These include water or juice fasting, which can last as long as several days, or eat-stop-eat fasting performed too often.
Moreover, it is particularly harmful to your hair and overall health to combine intermittent fasting with other forms of dieting (such as keto) or to restrict calorie intake too severely during the feeding window. This disrupts the balance of the fast and deprives your body of the resources it needs to grow and nourish your hair, as well as to function properly. If you think you can benefit from a personalised intermittent fasting regimen, always ask a nutritionist or your GP for recommendations.
It’s not always necessary to end your intermittent fasting if you’re experiencing telogen effluvium. Simply make sure you are getting the recommended dose of calories and nutrients and wait 3-6 months to see if your hair loss improves (in most cases, it should). If it doesn’t, a trichologist can help you determine if your hair shedding is indeed diet-related or if you are experiencing a different type of alopecia.
If you are so inclined, you can even try switching to a different, more permissive type of intermittent fasting to help stimulate your hair growth. However, you will still need to wait a few months before your hair starts growing back to the way it used to be.
Before and after hair restoration surgery, it is important to eat a well-balanced diet and get all the nutrients you need for a speedy hair transplant recovery and vigorous hair growth. This doesn’t necessarily mean you cannot engage in intermittent fasting; it only means you need to choose a dietary regimen that provides your body and scalp with all the resources they need for healing from your hair transplant.
About 2 weeks after surgery, you will likely be experiencing hair transplant shock loss, so you will be developing temporary hair shedding with or without intermittent fasting. However, if the stress of surgery is compounded by insufficient calorie intake or a nutritional deficiency, your healing process may be affected.
The best thing you can do is to ask your surgeon about the type of intermittent fasting that is safest for you and take their recommendations to heart. Our experienced surgeons at the Wimpole Clinic would be more than happy to answer all of your questions.
That largely depends on the type of intermittent fasting you prefer. Normally, a safe keto diet that supplies all the nutrients you need is as hair-friendly as moderate intermittent fasting, which does not involve long periods of food restriction or excessively low caloric intake during feeding windows. However, an unbalanced keto regimen can be as harmful as prolonged partial fasting that does not make up for the nutrients lost when restricting entire food groups. The best diet for healthy hair is a balanced and nutritious one, customised by a medical specialist to suit your specific dietary needs.
In the vast majority of cases, telogen effluvium resolves within a few months to half a year of onset. This condition can rarely become chronic, which means it can last from 6 months to several years if left untreated. However, partial or total permanent hair loss is almost unheard of due to dietary reasons alone. It can happen in exceptional situations, as a result of a nutritional deficiency that doesn’t respond to supplementation, but there are very few such documented cases.
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Paru Shukla is a qualified trichologist from the Institute of Trichologists, London and received the John Mason award for excellence.
She has been in the medical field since 2005 and has worked with quite a few eminent and well-known homeopathic clinics. She is now working as an in-house trichologist for the Wimpole clinic alongside Mr. Michael May (FRCS).
Paru Shukla is now the member of world trichology society and The Institute of trichologists.
Paru Shukla studied at the Institute of Trichologists in London and qualified as a trichologist in 2014. On graduation she was awarded the prestigious John Mason award for Excellence which is only awarded occasionally to candidates of distinction who have achieved the highest standards.
Since 2010 Paru has specialised in hair restoration solutions for Androgenetic Alopecia, more commonly known as male/female pattern baldness.
Passionate about her subject, Paru regularly attends and contributes to seminars and Conferences devoted to Hair Restoration and treatments.
Paru is also a member the World Trichology Society, The Institute of Trichologists and the European Hair Research Society. She started her medical career in 2005 in India where she trained and qualified as a Homeopathic practitioner working and studying in the leading specialist clinics in the region.
It was here she developed her interest in hair conditions, treatments and restoration becoming an active associate of the AHRS in India.
