MONDAY, July 7 (HealthDay News) -- If 156 million adults in the United States took better care of themselves, the average American would live 1.3 years longer, and the number of heart attacks would fall by 63 percent.
That's the conclusion of a joint study released Monday that combined the resources of the American Heart Association, the American Diabetes Association and the American Cancer Society.
"Prevention makes a difference," said study co-author Dr. Rose Marie Robertson, chief science officer of the American Heart Association. "You can live longer, maybe substantially longer, and you can have a much healthier life."
Even a more realistic scenario -- assuming, among other things, that just 20 percent of obese Americans lost weight -- would lead to major improvements in the country's overall health, researchers found.
There's a hitch: The health gains are entirely hypothetical. The study is an exercise designed to measure scenarios in which millions of Americans stopped doing things that are bad for them.
One scenario examined what would happen if the 78 percent of Americans aged 20-80 with risk factors that threaten their health didn't have those risk factors anymore.
Some smoke. Others are heavy, suffer from high cholesterol or high blood pressure, don't take aspirin when their heart attack risk is high, or have other risk factors they don't control through a healthy lifestyle or medication.
The researchers assumed that all those Americans -- 156 million of them -- managed to stop smoking, lose weight, and control other risk factors. Then they used a statistical model to predict what would happen.
Under this scenario, the number of heart attacks would fall by nearly two-thirds, and strokes would decline by almost at third, the researchers found.
The average life span of all Americans, meanwhile, would grow by 1.3 years. That may not sound like a lot, but it's an average number and could be much higher for younger people, Robertson said.
"You really prevent serious things," she said. "If you prevent those, then that person is healthier, so they're able to engage in the things they like doing. They live to see their daughter get married or get their kids through graduation, all the things that are stolen away."
The study looked at another scenario, considered "more feasible," in which smaller numbers of people started taking better care of themselves. Among other things, 20 percent of obese people would lose enough weight to stop being clinically obese, and 30 percent of smokers would quit.
Under that scenario, the number of heart attacks would fall by 36 percent and strokes by 20 percent.
The findings were expected to be published in both the July 29 issue of the journal Circulation and the August issue of Diabetes Care.
In another study released Monday, Norwegian researchers report that short bursts of intense exercise appear to do a better job of reducing metabolic syndrome -- linked to heart problems -- than longer, less vigorous exercise.
The intense bouts of exercise weren't exhausting, though, and didn't require participants to push their hearts to their top levels of endurance, said study co-author Ulrik Wisloff, a researcher with the Norwegian University of Science and Technology in Trondheim, Norway. The study will be published in the July 22 issue of Circulation.
Learn about heart-healthy habits from the American Heart Association.
SOURCES: Rose Marie Robertson, M.D., chief science officer, American Heart Association, Dallas. July 29, 2008; Ulrik Wisloff, Ph.D., researcher, Norwegian University of Science and Technology, Trondheim, Norway; Circulation and August 2008 Diabetes Care