* Thicker: Layers can add volume and movement to hair, making it appear thicker. This is especially true for fine or thin hair. Strategic layering can lift the hair at the roots and create the illusion of more body.
* Thinner: Excessive or poorly placed layers can make thick hair look thinner by removing too much bulk. This is particularly true if the layers are too short or choppy. Conversely, long layers can help to distribute weight and reduce bulk in very thick hair.
Ultimately, the effect of layers depends on the specific haircut, the hair type, and the desired result. It's best to consult with a hairstylist who can assess your hair and recommend the most suitable layering technique for your needs.