She allows the hair to grow below the chin, this helps elongate her face. When you have a round face, you want to avoid chin-length curly hair, or chin-length bobs.
Kelly sports sleek, graduated layers from her lips down. This helps remove bulk and weight from the sides.
Wispy, tapered ends de-emphasize roundness.
More hairstyles:
How to Look 10 Pounds Thinner in Photos
Photos: Celebrity Hair We Love
Photos of Short Hairstyles

