You might have heard about various fad diets that involve long periods of not eating. While some people swear by them, others maintain that there’s no reason to go through such drastic lengths just to lose weight or gain other health benefits. It turns out that the effects of prolonged fasting (and intermittent fasting) on hair loss and hair growth may be more nuanced than either of these two camps would like to admit. Here, we’re going to study how fasting affects hair loss and hair growth.

Effects on Human Physiology

For millennia, human beings have observed that one’s hair would grow differently during times of fasting than it would otherwise. For example, many Christians regularly fast on Wednesdays and Fridays in preparation for their Sunday meal with Jesus Christ. During such a fast, they believe they experience less hair loss and greater hair growth.

To test these beliefs, researchers at Oxford University examined different effects prolonged fasting has on metabolism (the process by which our bodies convert food into energy) and human physiology. Their findings suggest that prolonged fasting does affect hair loss and hair growth; however, to what extent is currently unknown. The effects may also vary from person to person based on an individual’s unique genetic makeup.

Effects on Hair Shaft Diameter

Intermittent fasting appears to have a positive effect on hair shaft diameter and density in women. A study published in Bioscience, Biotechnology, and Biochemistry found that certain methods of intermittent fasting may lead to reduced levels of dihydrotestosterone or DHT. DHT is often linked to genetic male pattern baldness and hair loss. As a result, researchers believe that intermittent fasting may help prevent hair loss in people who are susceptible to it.

People in the study who practiced alternate-day fasting experienced reductions in scalp-hair growth rate. However, those with diffuse (as opposed to common) forms of hair loss saw no improvement with regard to hair shaft diameter or frequency of split ends. This indicates that if you’re dealing with diffuse hair loss, your body may be producing too much testosterone for any dietary changes to affect your condition. According to these findings, long periods of time without food appear to have an adverse effect on female hair health.

Although more research is needed, practicing short-term fasts during intervals between larger meals seems to offer potential benefits for improving female hair health and preventing thinning or losing large amounts of hair altogether. It’s also important to note that reducing caloric intake alone won’t protect against thinning or significant shedding caused by genetics-fasting might help minimize thinning if you’ve noticed changes due to diet but still don’t know what triggers your condition.

Effects on Dermal Papilla Cells

Prolonged fasting-when you go for more than a day without eating-has been shown to negatively affect dermal papilla cells, which are located at the base of hair follicles. Researchers found that in mice, low levels of amino acids and insulin led to decreased cell viability and increased apoptosis. Prolonged fasting may lead to hair loss by damaging dermal papilla cells.

The good news is that just 24 hours after feeding again, researchers noted an increase in dermal papilla cell proliferation and no signs of DNA damage or mitochondrial dysfunction.

So if you’re planning on going on a fast, make sure it’s short-term. It might be worth giving your hair a break too: While there isn’t much research out there yet, we do know that protein plays an important role in healthy hair growth.

You can get protein from eggs, fish, nuts, and seeds (to name a few). Also, remember to drink plenty of water while fasting so your body stays hydrated. Prolonged fasting may lead to hair loss by damaging dermal papilla cells.

Effects on Hairs’ Anagen Stage

Long-term fasting may influence normal hair growth cycles. New research in mice suggests that prolonged fasting (intermittent or alternate-day fasting) can affect hair loss and growth by influencing their anagen stage, which is when hair grows. During anagen, which usually lasts for a few years, follicles are actively growing new hairs; these hairs then enter a shorter telogen stage before falling out.

In humans, fasting might suppress anagen and extend telogen phases to cause more visible hair loss as well as longer periods of non-growth. The study also found that prolonged fasting affected genes involved in hair growth, but not genes linked with hair loss. The findings suggest that prolonged fasting could increase susceptibility to baldness if it prolongs anagen stages beyond what’s typical for each person’s genetic makeup.

Skipping meals may promote weight gain – Study: Intermittent or alternate-day fasting diets do not appear to be any better than traditional calorie restriction diets at helping people lose weight long term, according to results from a large clinical trial published today in JAMA Internal Medicine. But there was one notable exception: Women who followed intermittent dieting plans seemed particularly prone to increased body fat around their abdomens — a problem area linked with diabetes and heart disease risk.

Effects on Hairs’ Telogen Stage

During prolonged fasting (greater than 72 hours), cells enter a stage of fasting known as telogen. Telogen is a natural part of hair growth. It’s not completely understood, but it may be related to damage caused by free radicals. In telogen, about 10% of hairs are resting on your scalp, which is where they rest until growth resumes after you eat again. However, when you’re on an intermittent fast or prolonged fast, some studies suggest that up to 50% of hairs may enter telogen prematurely during that time period.

This increased number of telogen hairs could explain why some people find they lose hair quickly while fasting. While there isn’t any research that shows what causes these hairs to go into telogen early, one theory is that prolonged fasting can trigger stress and other hormones associated with anxiety and depression. These hormones might cause more telogen hairs to fall out earlier than normal, according to researchers at Columbia University Medical Center.

Another study from Johns Hopkins University found similar results: Volunteers who were placed on an alternate-day fasting diet for six months had three times more telogen hairs compared with their baseline measurements before starting the diet.

Final Thoughts

Although research on fasting’s effects on hair loss and hair growth is still in its infancy, evidence suggests that prolonged fasting, as a part of intermittent fasting, may temporarily affect androgen levels and cause more hair follicles to enter into the resting phase. 

However, further research is needed before we can make any conclusions about whether prolonged fasting affects hair loss and stimulates healthy hair growth. When people do fast for religious or other reasons, they do so with no intention of losing weight or getting healthier.

You might also be interested in our article on How Vitamin B can help with hair loss.