Kybella permanently destroys the fat cells in the submental area creating your double chin, and they are gone for good. However, Kybella doesn’t eliminate every fat cell in the area, and the remaining ones may expand with weight gain. The volume of fat under your chin is much lower than in other areas, and minimal weight gain may not have a visible impact on your results, but it’s best to maintain a steady weight through a healthy diet and regular exercise to avoid an uneven appearance.