Researchers have discovered that intermittent fasting may slow down hair growth, sparking a conversation about its potential unintended effects. A recent study conducted on mice revealed that different fasting patterns, including a 16:8 intermittent fasting regimen and alternate-day fasting, resulted in a reduced speed of hair growth compared to mice with unlimited access to food. Complementing these findings, a clinical trial involving 49 healthy young adults showed an 18% reduction in hair growth speed for those following an 18-hour daily fasting schedule. These findings suggest that while intermittent fasting is a popular weight loss technique, it may come with a cost to hair health.
The study's results indicate that intermittent fasting can indeed lead to hair loss in some individuals. However, the effects are not uniform across all demographics, as the human population is highly heterogeneous. Bing Zang, Ph.D., emphasized this variability, noting that metabolic differences between species could account for the distinct impacts observed in mice and humans. While mice experience more severe effects due to their high metabolic rate, humans show milder impacts with some stem cells surviving, leading to slower regrowth.
“The human population is very heterogeneous, so the effects might be different for different people,” – Bing Zang, PhD
The mechanism behind hair growth disruption during intermittent fasting involves changes in hormonal regulation, metabolic pathways, and stem cell function in hair follicles. Hans J. Schmidt, MD, explained that this disruption affects the cyclic process of hair growth in mammals, particularly the transition from the resting phase to the growth phase. Without active growth periods, hair loss becomes more apparent.
“Hair growth in mammals follows a cyclic process with phases of growth, rest and shedding. Intermittent fasting has been shown to disrupt this cycle, specifically by affecting the resting phase to the growth phase. This disruption leads to slower or reduced hair growth in some instances. The mechanism involves changes in hormonal regulation, metabolic pathways, and even stem cell function in hair follicles. Normal periods of shedding will occur, but without active growth, there will be the appearance of hair loss.” – Hans J. Schmidt, MD
Ensuring adequate nutrition is vital to mitigate these side effects. Monique Richard, MS, RDN, LDN, highlighted the importance of consuming a balanced diet rich in essential nutrients like protein, vitamins A and B, iron, selenium, zinc, and essential fatty acids. Incorporating foods such as spinach, eggs, beans, fatty fish, nuts, seeds, and brightly colored produce can support hair health and overall well-being.
“Nutrients such as protein (providing essential amino acids like l-lysine); vitamins A,,, (and) ; B vitamins such as folate, biotin, niacin; and minerals such as iron, selenium, and zinc; and essential fatty acids aid in hair growth, skin health, and all organ function for that matter. Eating foods rich in these are necessary and beneficial. Foods like spinach and other leafy greens, eggs, beans, fatty fish and seafood, nuts like walnuts and Brazil nuts, seeds, and brightly colored produce will be beneficial to incorporate in a balanced diet.” – Monique Richard, MS, RDN, LDN
It is crucial to be cautious with dietary supplements that promise high levels of nutrients like biotin. Jennifer Cheng, DO, warned against supplements offering excessively high daily values of biotin as they may deplete other essential nutrients.
“Be careful to avoid the ever-so-popular supplements with 2000% or more of the daily value of biotin and other nutrients — they may deplete other essential nutrients. Look for nutrient-dense foods to sit down and enjoy at a table and with loved ones, not manufactured supplements engulfing your hard-earned cash,” – Jennifer Cheng, DO
To understand individual needs better and assess suitable fasting patterns or dietary intake adjustments, consulting with a registered dietitian nutritionist (RDN) is advisable. Richard emphasized the importance of personalized nutrition plans that consider various factors such as genetic predisposition and lifestyle.
“Assessing with a registered dietitian nutritionist (RDN) if the dietary intake is appropriate for the needs of an individual is essential as well as assessing if timing and type of fasting (i.e. 8 or 12 hours or a day between) may be appropriate for that person based on numerous factors such as other health considerations, goals, genetic predisposition, lifestyle, activity, and access to food are just a few,” – Richard
While the findings highlight potential drawbacks of intermittent fasting on hair growth and raise questions about its effects on skin wound healing and other tissues. Bing Zang pointed out ongoing research efforts aimed at identifying metabolites that could promote hair growth during fasting.
“We don’t want to scare people away from practicing intermittent fasting because it is associated with a lot of beneficial effects — it’s just important to be aware that it might have some unintended effects. We plan to examine how this process affects the regeneration activities in other tissues. We also want to figure out how fasting impacts skin wound healing and identify metabolites that could help the survival of HFSCs and promote hair growth during fasting.” – Bing Zang, PhD
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