Intermittent fasting has proven benefits for metabolic health, but a new study shows it can slow hair growth — at least in rats.
In a recent investigation, scientists subjected test subjects to intermittent fasting and concluded that, despite improvements in their metabolic health, their hair regeneration was much slowercompared to that of rats with access to food 24 hours a day, seven days a week.
Based on a small clinical trial conducted by the same research team, The same is likely to happen in humansalthough the process is less serious, given that we have a much slower metabolic rate and different hair growth patterns.
“We don’t want to scare people and stop them from practicing intermittent fasting because it is associated with many beneficial effects. It is just important to be aware that it may have some unwanted effects”, highlighted specialist Bing Zhang, from Westlake University in Zhejiang, China, cited by .
Before carrying out this study, the team hypothesized that fasting could be beneficial for skin tissue regeneration, the process by which old, damaged cells are replaced.
To test this, scientists examined hair growth in rats that were shaved and subjected to different intermittent fasting regimes. Some were fed on a time-restricted feeding (TRF) schedule that involved 8 hours of food access and 16 hours of fasting per day, while others were subjected to alternate day feeding (ADF).
This experience allowed us to discover that fasting inhibited hair regeneration. While mice in the control group – which had unlimited access to food – saw most of their hair regrow after 30 days, animals on both intermittent fasting regimens showed only partial hair regrowth after 96 days.
This inhibited hair growth happens because the stem cells in the hair follicle are unable to deal with the oxidative stress associated with switching the use of glucose to fat.
While cells from control rats began to become active around day 20 and remained so until their hair grew back, activated cells from animals undergoing intermittent fasting underwent apoptosis (programmed cell death) during prolonged periods of fast.
With the help of genetic engineering methods, the team revealed that this fasting-induced apoptosis was driven by a increased concentration of free fatty acids near the hair follicles, which caused a build-up of harmful oxygen radical species within the stem cells.
In a small clinical trial of 49 healthy young adults, researchers showed that a time-restricted diet involving 18 hours of fasting per day reduced the average rate of hair growth by 18% compared to the control group.
Still, additional studies will be needed to prove this effect, taking into account the study’s small sample size and its short duration, just 10 days.
For now, the scientific article with the results was published this month in Cell Press.
