Shaving Hair to Make it Thicker

A: If your goal is to simply get plenty of practice shaving your head, what you propose will be a great way to do it. However, it will not make your hair grow back thicker, nor will it increase the number of hairs produced by your follicles.
The hair on your head grows according to strict genetic and hormonal programming. The diameter of the hair shaft and the density of your follicles are determined deep beneath the surface of the skin, where a razor cannot reach. If simply shaving the head repeatedly could cure thin hair, pattern baldness wouldn't exist. In fact, shaving every single day for a month is more likely to cause severe scalp irritation, razor bumps, and ingrown hairs rather than a thicker mane.
As for the multiple hairs you are noticing, shaving doesn't multiply your follicles. What you are likely seeing are clusters of separate, tightly packed follicles that are finally emerging at the exact same time. Humans also naturally have "follicular units" where 1 to 4 hairs can emerge from a single pore. When you shave, you notice these clusters much more clearly than when the hair is long and flowing together.
What about the onion rumor for hair growth?
You actually heard correctly: there is some truth to the onion rumor, though it might not give you the results you are hoping for. A small clinical study showed that applying crude onion juice to the scalp twice a day could promote hair regrowth, but specifically for Alopecia Areata (an autoimmune condition where the body attacks hair follicles in patches), not for general genetic hair thinning.Onion juice is rich in sulfur, which is a building block for hair, and it acts as a mild stimulant to the scalp. However, it does smell incredibly potent, and it will not change your genetic hair thickness.
If you want to maximize your hair's potential from a practical level, focus on the environment it grows in:
• Scalp Health: Keep your scalp clean and free of excessive oil buildup, which can choke out follicles. Massage your scalp gently to encourage blood circulation.
• Nutrition: Hair is made of a protein called keratin. Ensure your diet is rich in lean proteins, healthy fats, and essential nutrients like iron, zinc, biotin, and Vitamin D.
• Cosmetic Helpers: If you choose to grow your hair out, use thickening shampoos and topical serums containing ingredients like caffeine or biotin. These products temporarily coat the hair shaft to add artificial girth and volume, giving the appearance of a fuller head of hair.
So, go ahead and shave your head if you like the look or want a fresh start; but don't expect the razor to rewrite your DNA.
©Hairfinder.com
See also:
Fine hair
Hair construction
Is there a difference between fine hair and thin hair?