It's not just how much weight you're carrying around that adds to your heart disease risk. A new government study finds the amount of time you've been obese plays a big role in how long the silent killer develops in your body.
Heart disease is the leading killer of men and women in the U.S., taking about 600,000 lives each year -- about one in four of all deaths.
"With a doubling of obesity rates for adults and a tripling of rates for adolescents during the last three decades, younger individuals are experiencing a greater cumulative exposure to excess adiposity [fat] during their lifetime," wrote the study's authors, led by government epidemiologist Dr. Jared Reis. "However, few studies have determined the consequences of long-term obesity."
Researchers collected data from nearly 3,300 white and black adults between the ages of 18 and 30, who in the 1980s, were enrolled in the National Heart, Lung, and Blood Institute's (NHLBI) CARDIA trial (Coronary Artery Risk Development in Young Adults Study).
Being followed for 25 years allowed researchers to track the participants' changes in risks from young adulthood to middle age. Patients were examined every two to five years by a doctor, and were also given CT scans at 15, 20 and 25 years into the study to look for coronary artery calcification.
The research was published July 16 in JAMA.
Calcium deposits in the coronary arteries can cause narrowing of the arteries that may increase risk for a heart attack, says the Mayo Clinic.
Calcium, combined with fat, cholesterol and other substances found in the blood form plaque. When plaque builds up in the arteries, a person has atherosclerosis, which can lead to serious health woes in addition to heart attacks, including strokes or death.
Reis, a researcher at the NHLBI's division of cardiovascular sciences, points out that the presence of coronary artery calcification could help predict the development of heart disease.
The study results suggest becoming obese at an earlier age could have major heart implications by middle age.
Researchers found coronary artery calcification in more than 27.5 percent of people, about 900 of the participants. The physical exams confirmed that the presence and extent of the artery blockage was associated with the length of time the participant was obese.
For example, about 38 percent of people who were obese for more than 20 years had arterial calcification, compared to about 25 percent of those who never were obese. Significant calcification was also more common in people who had been obese for more than 20 years than those who weren't obese.
People with abdominal obesity, who carried weight around their stomach region, had higher rates of calcification.
Overall, more than 25 percent of the subjects with overall obesity for more than two decades experienced progression of coronary artery calcification, compared with 20.2 percent. For those with abdominal obesity for more than 20 years, almost 28 percent had progressive coronary artery calcification, as opposed to 19.5 percent of those with zero years of obesity.
Reis told Bloomberg that his research may give doctors more to think about when trying to assess an overweight or obese patient's risk for health problems.
"What our study suggests is if we're measuring only body mass index [BMI] and waist circumference we may be underestimating the health risks of obesity by not measuring the duration," Reis, an epidemiologist at the NIH's National Heart, Lung, and Blood Institute in Bethesda, Maryland, said in a telephone interview.
according to U.S. estimates, raising their risk for obesity-related conditions including the aforementioned heart disease, stroke, Type 2 diabetes and certain types of cancer
Dr. Mariell Jessup, president of the American Heart Association, told USA Today that there may soon be another epidemic on the country's hands if young people don't do something about their health.
"If we had to target one particular group of Americans for the treatment of obesity, we certainly want to work on children and young adults," said Jessup. "If we don't tackle obesity in these young people, there will be an epidemic of coronary artery disease just like there is currently an epidemic of obesity."