You know smoking is bad for your health. Ditto heavy drinking, inactivity and poor diet.

You know smoking is bad for your health. Ditto heavy drinking, inactivity and poor diet. But you may not recognize that the four common bad habits combined can subtract your lifetime, said a study in Monday's Archives of Internal Medicine. [File Photo]

But you may not recognize that the four common bad habits combined can subtract your lifetime, said a study in Monday's Archives of Internal Medicine.

The study tracked nearly 5,000 British adults for 20 years and correlated these behaviors with risk of disease and death.

In the study, 314 people had all four unhealthy behaviors. Among them, 91 died during the study, or 29 percent. Among the 387 healthiest people with none of the four habits, only 32 died, or about 8 percent.

These habits combined substantially increased the risk of death and made people who engaged in them seem 12 years older than people in the healthiest group, said lead researcher Elisabeth Kvaavik of the University of Oslo.