The Hidden Cost of Fasting: How Dieting May Slow Your Hair Growth

Fasting has been touted as a straightforward way to improve health, but new research is highlighting an unexpected consequence: hair growth. A recent study in the journal Cell found that common fasting schedules can slow down hair regrowth in mice, and a small clinical trial suggested a similar effect in humans.

While intermittent fasting may still have its benefits, a Cochrane review has cast doubt on its effectiveness for weight loss, which could change the calculus for those who are relying on it to see results. The review examined 22 studies involving over 1,900 adults and found that intermittent fasting made little to no difference in weight loss compared to traditional dietary advice.

The Hair Growth Study: What Does It Mean?

Researchers at Westlake University shaved mice and then tested the effects of two common fasting schedules. The results showed that mice with unlimited food had regrown most of their hair after 30 days, while those on a fasting schedule still had only partial regrowth after 96 days.

A small clinical trial involving 49 healthy young adults found that daily 18-hour fasts resulted in an average 18% lower rate of hair growth compared to controls. The researchers emphasized that more studies are needed to confirm the effect, and that it's not a reason to abandon intermittent fasting altogether.

What Happens Inside the Hair Follicle?

The slowdown in hair growth is linked to oxidative stress during extended fasting. When the body shifts towards using fat as fuel, nearby fat tissue releases free fatty acids, which can lead to a buildup of reactive oxygen species and stem cell apoptosis.

Interestingly, the authors found that the effect was independent of calorie reduction and changes in circadian rhythm, suggesting it's not just about eating less. Boosting antioxidant defenses helped hair follicle stem cells survive fasting in mice, including with topical vitamin E - a finding that should be taken as a lab result, not a supplement recommendation.

The Weight Loss Evidence: A Reality Check

For those who started fasting for weight loss, the latest research suggests it may not be the magic solution they were hoping for. The Cochrane review found that intermittent fasting made little to no difference in weight loss compared to traditional dietary advice.

The review also noted limited and inconsistent reporting of unwanted events, and none of the studies reported people's satisfaction with fasting - which is crucial when trying to stick with a plan for months, not just weeks.

Fasting: A Double-Edged Sword?

While the hair findings may seem alarming, they don't necessarily mean that intermittent fasting is "bad". In fact, the Cell Press team noted metabolic benefits in the mice even as hair regeneration slowed. This highlights the complex interplay between different bodily systems.

Other research has shown that fasting can have contradictory effects - for example, it may boost intestinal stem cell regeneration, but also increase the risk of precancerous polyps if cancer-related mutations occur during refeeding.

Who Should Be Cautious About Fasting?

Medical experts warn that fasting is not suitable for everyone, particularly without medical supervision. Certain groups should exercise caution, including pregnant or breastfeeding women, those with diabetes medications, and individuals with conditions like seizure disorders.

Hair changes can be a visible indicator of underlying issues, such as thyroid disease or iron deficiency anemia. It's essential to consult with a healthcare provider before starting any fasting regimen.

Fasting: A Balanced Approach

So should you quit fasting altogether? Not necessarily. However, it's wise to choose a schedule that allows for consistent nutrient intake and avoid extreme rebound binges. Monitor your overall health and adjust your approach as needed - energy levels, sleep quality, mood, training performance, and hair growth can all be early signals that the plan is not working.

Ultimately, it's crucial to prioritize stability over extremes and watch more than just the scale for signs of success or failure.