Jan. 10, 2006 -- Adults who are overweight or obese have an increased risk of dying from heart disease and diabetes later in life, even if they don't have cardiovascular risk factors such as high blood pressure or high cholesterol, new research shows.
But the new research, published in the Dec. 11 issue of The Journal of the American Medical Association, offers some of the strongest evidence yet that carrying excess weight is an independent risk factor for hospitalization and death from cardiovascular causes.
"Study after study has shown that overweight and obesity are associated with higher risks for many health outcomes," researcher Lijing L. Yan, PhD, MPH, tells WebMD. "What hasn't been clear is whether this risk is driven by the association with other risk factors."
Study Spanned Decades
Yan and colleagues at Northwestern University in Chicago examined the relationship between excess weight earlier in life and illness and death after age 65 by following more than 17,600 people for decades.
The participants were between the ages of 31 and 64 when enrolled in a Chicago-based heart registry between 1967 and 1973. None had heart disease or diabetes at enrollment, and the average time of follow-up was 32 years. Most participants were white.
Cardiovascular risk at enrollment was considered low if the participant met three criteria:
People were defined as normal weight, overweight, or obese by their body mass index (BMI). The BMI is calculated using a person's weight and height measurements. BMI between 18.5 and 24.9 is considered normal weight, 25-29.9 overweight, 30 and greater obese.
The researchers found that the risk of dying from heart disease was 43% higher for study participants who were obese but also met these qualifications for low cardiovascular risk than for normal-weight, low-risk participants.
Compared with their normal-weight, low-risk counterparts, the obese people in the study also had four times the risk of hospitalization for heart disease and 11 times the risk of dying of diabetes.
Low-risk people who were overweight but not obese had a higher risk of death and hospitalization from cardiovascular disease and diabetes than their normal-weight counterparts and a lower risk than people who were obese.
"Our study is unique in that we had a very long follow up of over 30 years," says Yan, who is a research assistant professor at Northwestern and an assistant professor at China's Peking University.
"This is only one study, but it adds to the existing picture of the health consequences of obesity. It is important to try and maintain a healthy body weight and to work to lose weight or at least not gain more weight if you already are overweight or obese."
Lose Weight, Get Moving
The American Heart Association has long recognized obesity as a major risk factor for cardiovascular disease -- one of six modifiable risk factors along with smoking, high cholesterol, high blood pressure, physical inactivity, and diabetes.
AHA spokesman and cardiologist Gerald Fletcher, MD, of the Mayo Clinic in Jacksonville, Fla., tells WebMD that while most people who are obese also have other cardiovascular risk factors, this isn't always the case.
That means walking or doing something else to get your heart rate up from 30 to 60 minutes a day, six to seven days a week, he says. He adds that only about one in four people in the U.S. get enough cardiovascular exercise.
"You don't have to do it all at once," he says. "You can spread it throughout the day, but our data tell us that most people still aren't doing it. And about 17% of the country is not exercising at all."