Here's why:
* Hair thickness is determined by genetics: The diameter of your hair follicle is genetically determined. This dictates how thick each individual strand of hair will be. Thinning or cutting hair doesn't change your DNA or the size of your follicles.
* The blunt cut illusion: When you cut the ends of your hair straight across (a blunt cut), it can *appear* thicker for a short time. This is because all the hairs are the same length at the ends, creating a denser-looking edge. As the hair grows, it naturally thins out again as different strands grow at slightly different rates and get trimmed at different times.
* New growth feels different: Short, newly grown hair often feels coarser and thicker than the longer, tapered ends of older hair. This can also contribute to the perception of increased thickness after cutting or thinning.
* Thinning shears remove volume: Thinning shears specifically remove bulk from your hair by cutting some strands shorter than others, which reduces density and makes the hair feel lighter. They do not affect the hair follicles.
In summary: Thinning your hair is a styling technique and does not alter the actual thickness or growth rate of individual hairs. The perceived thickness change after a cut is usually temporary and due to the visual effect of a blunt cut or the sensation of new growth.