Does Intermittent Fasting Cause Hair Loss?

As many of you know, I have long advocated in favor of intermittent fasting. Intermittent fasting is widely praised for its many health benefits, particularly its positive effects on metabolic health. But a recent study reveals that fasting might have an unexpected side effect: slower hair regrowth. While the findings are based mainly on research in mice, a small human trial suggests a milder impact on humans. Let’s break down the key points of this intriguing study.

What Did the Study Find?

Researchers discovered that intermittent fasting could impair the activity of hair follicle stem cells (HFSCs), which are essential for hair regrowth. During fasting periods, the body shifts from using glucose to burning fat. This metabolic switch releases free fatty acids near hair follicles, triggering oxidative stress that damages HFSCs.

In mice, prolonged fasting caused HFSCs to undergo apoptosis—a form of programmed cell death—leading to significantly slower hair regrowth compared to mice with constant access to food. Human HFSCs showed a similar response in lab tests, although the effects were less severe due to differences in human metabolic rates and hair growth patterns.

Human Impact: What About Hair Growth in People?

A small clinical trial involving 49 healthy adults tested the effects of a time-restricted diet (18 hours of fasting daily). Participants on this regimen experienced an 18% reduction in hair growth speed compared to those who ate without time restrictions. While the reduction in hair growth was noticeable, the effect was mild, and hair still regrew.

The study’s authors caution that the human results may vary widely due to individual differences, such as metabolic rates and genetic factors. Additionally, the trial’s short duration (10 days) and small sample size mean more research is needed to fully understand the implications for humans.

Antioxidants to the Rescue

The good news is that the negative effects of fasting on HFSCs might be mitigated. The study found that antioxidants like vitamin E can protect HFSCs from damage caused by oxidative stress. When researchers applied vitamin E topically or enhanced antioxidant activity genetically in mice, HFSCs survived fasting periods more effectively, and hair regrowth improved.

This finding suggests that incorporating antioxidants into your diet or hair care routine might help counteract potential hair growth challenges while fasting.

Why Does This Happen?

The researchers explained that HFSCs are less equipped to handle the oxidative stress and free fatty acids released during fasting. Unlike epidermal stem cells (which maintain the skin barrier), HFSCs have lower antioxidant capacity, making them more vulnerable. This difference might explain why fasting doesn’t seem to affect skin regeneration but does slow hair regrowth.

Should You Avoid Intermittent Fasting?

The study’s lead author, Dr. Bing Zhang of Westlake University, emphasizes that intermittent fasting still offers many benefits, including better metabolic health and increased stress resistance for other types of stem cells (e.g., those in blood, muscle, and intestinal tissues). However, it’s essential to be aware of possible unintended effects, especially if hair health is a concern.

If you’re practicing intermittent fasting and notice slower hair regrowth, consider:

• Incorporating antioxidants into your diet (e.g., vitamin E-rich foods like almonds, spinach, and sunflower seeds).
• Using antioxidant-based hair care products.
• Monitoring your hair health during extended fasting periods.

What’s Next in Research?

The study opens up new questions about how fasting affects other types of stem cells in the body. Future research will explore its impact on skin wound healing and other regenerative processes. Researchers also hope to identify specific metabolites that could support HFSC survival and promote hair regrowth during fasting.

Takeaway

Intermittent fasting offers numerous health benefits, but it may come with trade-offs, including slower hair regrowth. While the effects appear to be mild in humans, particularly when compared to mice, being proactive by supporting your stem cells with antioxidants might help mitigate this unintended side effect. As with any lifestyle change, balance and awareness are key to optimizing your overall health.