Excess fat under your chin often develops as you gain weight, but many people end up with a double chin even when they haven’t put on extra pounds. Your genes contribute to the problem, sometimes leading to submental fat regardless of weight.
Aging also has an impact. As you get older, your skin naturally loses its tone and starts to sag, while the layer of fat under your skin begins to give in to the effect of gravity. As a result, you end up with a double chin.