Intermittent Fasting May Impact Your Hair: What You Should Know

Intermittent fasting, also known as time-restricted eating, has gained popularity for its potential health benefits, including weight loss and reduced inflammation. It works by limiting the hours during which you eat, which may help prevent overeating without the need to count every calorie. However, this eating pattern may come with some unexpected drawbacks—particularly when it comes to your hair health.

According to registered dietitian Jana Greene Hand, intermittent fasting isn’t suitable for everyone, and those adopting the diet need to be mindful of the nutrients they consume during their eating window. Hand told Health Digest that while the practice offers several health advantages, it may also result in some unpleasant effects. “While there are plenty of benefits to intermittent fasting, such as weight loss and reduction of inflammation in the body, there can be unpleasant side effects as well, such as the thinning of hair,” she explained.

One of the main concerns is the calorie restriction that often accompanies intermittent fasting. Hand warned that such restriction can lead to nutrient deficiencies, which may interfere with the body’s ability to grow strong, healthy hair. “In order to grow thick beautiful hair, the body needs ample protein, iron, zinc and B vitamins,” she said. “Intermittent fasting has been linked to deficiencies of these vital nutrients.”

Beyond nutrient loss, hormonal changes triggered by intermittent fasting may also stunt hair growth. A 2021 study in Endocrinology and Metabolism found that strict eating schedules can cause unexpected hormonal fluctuations. These disruptions, in turn, may affect both the look and length of your hair.

Hand pointed out that intermittent fasting raises cortisol levels, a stress hormone known to trigger chronic oxidative stress in the body. “Cortisol puts the body into chronic oxidative stress, which can negatively impact hair growth,” she said. A 2025 study in *Cell* echoed these concerns, revealing that intermittent fasting can lead to oxidative damage that affects hair follicles and disrupts their ability to produce hair.

Another hormonal factor that can interfere with hair health is thyroid function. Hand explained, “Intermittent fasting has also been linked to the inhibition of thyroid function which slows down hair follicle activity and can lead to dry, brittle hair and hair loss.”

Despite these potential risks, it’s still possible to support healthy hair while practicing intermittent fasting—if you follow a few essential dietary strategies. Hand offered three key tips to help protect your hair during fasting.

First, ensure you’re eating enough protein, which is critical for hair growth. Great sources include eggs, tofu, chicken, fish, and lean beef. Second, incorporate iron- and zinc-rich foods such as nuts, seeds, and beans. Hand also recommends including healthy fats like avocado, olive oil, and fatty fish to nourish the hair.

Lastly, Hand suggested modifying your fasting window. “To maximize your hair growth, consider shortening your fasting window from 16 hours to something less extreme, like 12-14 hours,” she advised.

By practicing a balanced approach and paying close attention to nutrient intake, you can reap the benefits of intermittent fasting without compromising your hair health.