Certain bad habits including smoking, drinking too much alcohol, inactivity and poor diet can age you by 12 years, new research shows.

The findings are based on a study of nearly 5,000 British adults who were tracked for 20 years.

About a third of those with all four bad habits died. The most common cause of death was heart disease and cancer.

On the flip side, the healthiest group included non-smokers, teetotalers, those who exercised two hours a week and those who ate fruits and veggies three times a day. Only eight percent of them died.

"You don't need to be extreme" to be in the healthy category, said lead researcher Elisabeth Kvaavik of the University of Oslo. "These behaviors add up, so together it's quite good. It should be possible for most people to manage to do it."