Benefits of Fasting for Men's Health: What We Know About Skin and Hair

Short answer: Intermittent fasting is an eating pattern with set times for eating and set times for little or no food. Some adults lose weight with it, but it has not been shown to speed up hair or beard growth or to improve skin, and it is not right for everyone.

Intermittent fasting has gone from a niche habit to a mainstream wellness trend, and many men ask what it means for their skin, hair and beard. This guide covers what research suggests about fasting and general wellbeing, what is and is not known about hair and skin, who should talk to a doctor first, and how to keep a simple grooming routine going whatever your eating pattern.

Key takeaways

• Intermittent fasting is a way of timing meals, not one diet, and most studies track weight, blood sugar and blood pressure.
• For weight, results are often similar to other ways of cutting calories, and long-term effects are not yet known.
• Fasting is not shown to speed up hair or beard growth, and crash dieting or rapid weight loss can cause temporary hair shedding.
• Research on fasting and skin is scarce, so daily washing and moisturizing remain the basics.
• Talk to a doctor before you start, especially if you have a medical condition or take medication.

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What is intermittent fasting?

Intermittent fasting is an eating pattern that alternates between eating and fasting, often described as a schedule or cycle. It is mainly about when you eat rather than which foods you eat, and it is not meant to be starving yourself. Because most people already fast while they sleep, time-restricted schedules are a popular starting point: with 16:8, you fast for 16 hours and eat within an eight-hour window, for example 11 a.m. to 7 p.m. Cleveland Clinic describes the main schedules like this:

What does research say about fasting and general health?

Research suggests intermittent fasting can help some adults lose weight, with results often similar to other ways of cutting calories. Some short studies report improvements in blood sugar and blood pressure, but long-term effects are not yet known. Harvard Health describes the evidence on weight loss as murky, because studies are often small and short, and in one year-long trial, adding an eight-hour eating window to a calorie-reduced diet did not lead to more weight loss than the same diet without a time limit. Weight lost by any method can include some muscle, so Harvard Health also advises pairing fasting with resistance training. What you eat still matters: Canada's Food Guide recommends plenty of vegetables and fruits, whole grains and protein foods, with water as your drink of choice.

Does fasting make your hair or beard grow faster?

There is no good evidence that it does, and the closest research points the other way. Most fasting studies track weight, blood sugar and blood pressure, and we could not find a study that looks at fasting and beard growth. A 2024 study in the journal Cell found that intermittent fasting slowed hair growth in mice, and a short randomized trial in adults, who had a small patch of scalp shaved, pointed the same way. The human trial was short, and what fasting does to hair over the long term in people is still unclear.

Eating too little is a separate concern. MedlinePlus lists crash diets, especially those low in protein, as a cause of temporary hair shedding, and Cleveland Clinic says rapid weight loss and restrictive diets can have the same effect. If you fast, eat enough in your eating window, and see a doctor if you notice sudden or patchy shedding.

Does fasting change how your skin looks?

No one can say for sure, because the research is thin. A 2019 review of fasting and skin concluded that research on how fasting affects skin conditions is scarce and of poor quality. One small 2023 trial of a five-day "fasting-mimicking" diet in 45 women reported higher skin hydration, but that is a different diet from everyday intermittent fasting.

The American Academy of Dermatology keeps its beard skin care simple: wash your face and beard every day with a gentle cleanser made for your skin type, pat dry, and moisturize while the skin is still slightly damp. Drink water through the day, including during your fast. If you notice a rash or other skin changes after changing how you eat, see a doctor or dermatologist.

Who should talk to a doctor before fasting?

Anyone thinking about fasting should check with a doctor first, because intermittent fasting is not safe for everyone. Cleveland Clinic and Harvard Health point to these groups in particular:

• People with diabetes or low blood sugar, or who need to eat with their medication.
• Anyone with a history of an eating disorder, who should not fast without medical supervision.
• People who are pregnant, breastfeeding or malnourished, and children.
• Anyone with a chronic medical condition.

Fasting can also change when you should take medication, so ask your doctor before you adjust any dose times. If you train hard, you may need to adjust the schedule. Even if none of this applies, a short conversation about which schedule, if any, suits you is worth having.

How do you start fasting safely?

If your doctor agrees, start gently and choose a schedule you can keep up. Cleveland Clinic suggests a 14:10 or 16:8 window as a first step and advises avoiding extreme forms of fasting.

1. Pick an eating window that fits your day, such as 11 a.m. to 7 p.m., and keep it similar from day to day.
2. During the fast, stick to water, carbonated water, black coffee or unsweetened tea. Anything with calories breaks the fast.
3. In your eating window, follow Canada's Food Guide: plenty of vegetables and fruits, whole grains and protein foods, and fewer highly processed foods.
4. If you are losing weight, add resistance training.
5. If you feel dizzy, very weak or unwell, stop fasting and talk to your doctor.

How does a grooming routine fit with fasting?

Your grooming basics stay the same whatever your eating pattern. Grooming products are cosmetics: they cleanse, moisturize and condition the surface of skin and hair, and they do not change what happens inside the body. Apply them after washing, while the skin is still slightly damp. For normal to dry skin, the AAD suggests beard oil, used sparingly because you can always add more. Here is how our products fit in:

• Beard oil moisturizes the skin under the beard and softens the hair. Organic Beard Oil | African Musk has a warm, woody scent, and Organic Beard Oil | Classic is fragrance-free.
• Hair oil conditions hair, tames frizz and adds shine. Organic Hair Oil | Lavender is a light, fast-absorbing oil made with lavender essential oil, and you can browse all our organic hair care products.
• The Activated Charcoal Facial Cleanser is a plant-based cleansing bar for face and body.

For the full steps, see our guides to washing your beard, hair care routines and diet, food, exercise and hygiene for men.

Frequently asked questions

Is intermittent fasting good for men's health?

It can suit some men, but the evidence is mixed. Studies suggest some adults lose weight and see short-term changes in blood sugar and blood pressure, yet results are often similar to other ways of cutting calories, and long-term effects are unknown. Intermittent fasting is not right for everyone, so talk to a doctor before you start, especially if you take medication or have a medical condition.

Does fasting make a beard grow?

Fasting has not been shown to change beard growth, and we could not find a study that tests it. The closest research, on hair on the head, found that intermittent fasting slowed hair growth in a shaved patch of scalp. What you can control is the skin under the beard: wash daily with a gentle cleanser, moisturize, and use beard oil sparingly.

Can fasting cause hair loss?

Eating too little can cause temporary hair shedding. MedlinePlus lists crash diets, especially those low in protein, as a cause, and Cleveland Clinic says rapid weight loss and restrictive diets can have the same effect. If you fast, eat enough in your eating window, including protein, and see a doctor if you notice sudden or patchy shedding.

What can you drink while fasting?

Cleveland Clinic says water, carbonated water, black coffee and unsweetened tea are acceptable during a fast, while anything with calories breaks it. It also advises limiting artificial sweeteners, which may take you out of a fasting state. Canada's Food Guide recommends making water your drink of choice, and staying hydrated matters whatever your eating pattern.

What is autophagy, and does fasting change it?

Autophagy is the process cells use to recycle some of their own contents. Yoshinori Ohsumi received the 2016 Nobel Prize in Physiology or Medicine for his discoveries of the mechanisms behind it. Harvard Health notes that research on how fasting affects cell processes comes mainly from animal studies, with some human trials. Whether an everyday eating window changes autophagy in people, and whether that shows in your skin, is not established.

Should I talk to a doctor before I fast?

Yes. Cleveland Clinic advises contacting a healthcare provider before you start, because fasting can affect the timing of medication and is not safe for some people, including those who are pregnant or breastfeeding or have a history of an eating disorder. Ask your doctor whether fasting suits you and which schedule, if any, is safest.

Explore our full grooming range: beard care, hair care and skincare, all made in Canada with certified organic ingredients.

Sources

• Cleveland Clinic: Intermittent fasting: what it is, benefits and schedules
• Harvard Health: Should you try intermittent fasting for weight loss?
• MedlinePlus: Hair loss
• Cleveland Clinic: Telogen effluvium (temporary hair shedding)
• American Academy of Dermatology: A dermatologist's top tips for a healthy beard
• Canada's Food Guide: Healthy eating recommendations
• Chen H, et al. Cell, 2025;188(1):157-174 (published online December 2024): intermittent fasting and hair growth in mice and in a randomized trial in adults.
• Bragazzi NL, et al. Nutrients, 2019;11(2):249: fasting and its impact on the skin, a review of the literature.
• Maloh J, et al. J Clin Med, 2023;12(5):1710: a fasting-mimicking diet and skin hydration in 45 women.

Knightsmen Grooming products are cosmetics. This guide is general information, not medical advice. If you have a skin or scalp condition, or sudden changes in your hair, see a doctor or dermatologist.