A double chin, often associated with aging, is the accumulation of excess fat or loose skin beneath the chin, resulting in fuller appearance in the neck area. As people age, changes in metabolism and hormonal fluctuations can lead to the gradual accumulation of fat under the chin. This excess fat can contribute to the appearance of a double chin. Over time, the skin loses its elasticity due to a decrease in collagen and elastin production. This can result in sagging skin, making the area under the chin more prone to drooping and contributing to the appearance of a double chin.