Hair Growth Factors: The Basics

In the previous article, we discussed how different internal and external factors could influence your hair growth to be stunted. So, now you already know why your hair seems to have stopped growing. But here’s another question: what determines how fast it grows, anyway?

Today, we’ll discuss the basic hair growth factors that dictate how fast--or how slow--your hair grows.



It’s hard to imagine that the seasons could have anything to do with our hair, right? But some studies are suggesting that it may be possible. According to researchers, hair actually grows faster during the summer months. The effect isn’t that huge, but the average increase is roughly 10% for most months and as high as 70% for the peak period.


Age is one of the most important hair growth factors. People who are between the ages of 15 and 30 tend to experience the fastest hair growth, since this is the time when the anagen phase of your strands is at its longest.

The anagen phase usually lasts for about 5-7 years, but for some people over 30, their anagen phase is much shorter, with their strands entering the telogen phase before reaching their optimum length.This phenomenon explains why people over 30 have trouble growing their hair as long as it was when they were younger. This also explains receding hairlines and hair loss in older people, something that’s particularly common in men.


Although bald spots are more common in men, did you know that male hair actually grows faster than female hair? We always joke about how often our guy friends or guy relatives have to go to barber shops to get a haircut, but it turns out that it’s actually rooted in science. 

The reason for this is testosterone, one of the different classes of hormones that make up the androgens, or male hormones. Testosterone affects the hair follicles, which is why men have generally more hair than women. This hormone is basically what allows them to have facial hair and body hair. As a side effect, it also causes them to grow their scalp hair much faster than women.


You know how we said sex affects hair growth because of testosterone levels in males? Well, it’s not the only thing that affects hair growth. Race also comes into play too.

Ever noticed how Asian men, particularly East Asians like Chinese, Japanese, and Koreans, don’t get a lot of facial and body hair? That’s because although their testosterone affects their hair follicles, they work differently for Asians. There are two common findings for this. One, Asian men tend to have less androgen receptors on their faces and bodies. Two, Asian male bodies don’t have much of the enzyme that converts testosterone to its androgenic form, the main thing that stimulates hair follicles.

Other than that, Asians actually experience the fastest hair growth, since they have the longest anagen phase. The average Asian also has thicker, coarser hair when compared to the average African or the average Caucasian. This is due to the shape of the hair follicles, which is also determined by race.


A good way to see how fast or slow your hair is growing is to take a look around your own family. How often does your father or your brother go for a haircut? Do they need to shave often or else they’ll look scruffy? Does your mother still keep her hair long despite her age?

If your family is blessed with lush, thick hair then it’s highly likely that your hair grows the same way. Sadly, if most of the older people in your family already have receding hairlines and grey hair starting from the age of 35, then there’s really not much you can do. There’s no way to combat your own genes. At the very least, knowing your family’s hair quality is a good way to gauge your own.


How healthy you are greatly dictates how fast your hair will grow. People who eat plenty of junk foods, lead bad lifestyles, get stressed on a regular basis, and are always sick tend to have more hair growth issues than someone in good health. That’s why it’s very important to take care of yourself if you want your hair to grow long and beautiful.

In the next part of this series, we’ll discuss the best foods that you can eat if you want to speed up your hair growth. Don’t forget to stay tuned to the ZALA blog for more!

February 23, 2020
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