Some people are born with fewer or thinner strands, but if your part is getting bigger or your ponytail is getting thinner, hair loss could be to blame. Additionally, thin hair is more prone to breakage, and as one gets older, hair growth slows down, and the damage is more obvious. Since thickening shampoos typically contain fewer conditioning ingredients, they are less likely to weigh hair down, which can help give the appearance of thicker, fuller hair.