Intermittent fasting has proven benefits for metabolic health, but a new study shows that it could slow hair growth — at least in mice. Researchers report that mice subjected to intermittent fasting regimes showed improved metabolic health but slower hair regeneration compared to mice with 24/7 access to food. A similar process might occur in humans, based on a small clinical trial that the team also conducted, but it’s likely to be less severe since humans have a much slower metabolic rate and different hair growth patterns compared to mice.