A 2001 Danish study found that people who look younger than their age live a longer life on average. The test conducted physical and cognitive tests on more than 1,800 pairs of twins over the age of 70 and tracked how long the twins survived over 7 years. The test found that the people who looked younger than their age were more likely to survive, even after factors like gender and environment were adjusted.
There may be a possible biological reason. People who looked younger had longer telomeres, a DNA component that is linked to aging. People with shorter telomeres are assumed to age faster. In the study, the people with longer telomeres looked younger than their age.