Here's why:
* Hair growth happens at the root: Hair thickness is determined by the hair follicle, which is located beneath the skin. Shaving only cuts the hair shaft at the surface and has no effect on the follicle.
* Hair tapers: When hair grows out naturally, the tip is often tapered and finer due to wear and tear. When you shave, you're cutting the hair straight across, so the new hair feels blunt and may initially *seem* thicker. This is just because you're feeling the full width of the hair shaft all at once.
* Visual effect: A short, uniformly cut hairstyle can also create the illusion of thicker hair overall, as the hair stands up more and gives the appearance of more volume.
Factors that do influence hair thickness and growth include:
* Genetics: This is the primary factor determining your hair's natural thickness, color, and growth rate.
* Age: Hair tends to become thinner and grow more slowly as you age.
* Hormones: Hormonal changes (like during puberty, pregnancy, or menopause) can affect hair growth and thickness.
* Nutrition: A healthy diet rich in vitamins and minerals is essential for healthy hair growth.
* Health conditions: Certain medical conditions and medications can affect hair growth and thickness.
* Hair care: Excessive heat styling or harsh chemical treatments can damage hair, leading to breakage and the appearance of thinner hair.
In summary: Shaving your head won't change the fundamental thickness of your hair. The perception of thicker hair after shaving is just an illusion due to the blunt ends and uniform length of the newly grown hair.