Dead people had bad habits

AP reports on a widely publicized study:

Four common bad habits combined — smoking, drinking too much, inactivity and poor diet — can age you by 12 years, sobering new research suggests.

The findings are from a study that tracked nearly 5,000 British adults for 20 years, and they highlight yet another reason to adopt a healthier lifestyle.

Overall, 314 people studied 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.

The risky behaviors were: smoking tobacco; downing more than three alcoholic drinks per day for men and more than two daily for women; getting less than two hours of physical activity per week; and eating fruits and vegetables fewer than three times daily.

No, this study does not prove that those bad habits age you. Maybe the exercise does not make you healthier or make you live longer at all. Maybe the folks who are in poor health are about to die are physically incapable of exercise. Then this study would make it appear that exercising is making people live longer, but the exercise could be just a symptom, not a cause.