Just one month after the American Medical Association (AMA) classified obesity as a disease, a study published July 17 in JAMA adds weight to the argument that preventing or delaying the onset of obesity as a young adult offers health dividends later.

Jared P. Reis, PhD, of the cardiovascular sciences division at the National Heart, Lung, and Blood Institute in Bethesda, Md., and colleagues used the CARDIA (Coronary Artery Risk Development in Young Adults) study to assess whether duration of overall and abdominal obesity beginning in young adulthood was associated with the presence of coronary artery calcification (CAC) and its progression. Obesity shares many risk factors with CAC, which can predict coronary heart disease events.

The community-based CARDIA study enrolled a racially diverse group of young adults between 1985 and 1986 who at that time were 18 to 30 years old and followed them through three decades. Weight, height and waist circumference were obtained at baseline and then at two, five, seven, 10, 15, 20 and 25 years.  

Reis et al’s study sample totaled 3,275 participants who at baseline had a body mass index of less than 30 or a waistline circumference of less than 102 cm for men and less than 88 cm for women.

The researchers determined the presence of CAC at year 15, 20 and 25 using CT. They defined the presence of CAC as a calcium score greater than 0 Agatston units and CAC progression as incident CAC at year 25 or an increase in CAC score of 20 Agatston units or greater. Other clinical measures included blood pressure, cholesterol, glucose and plasma C-reactive protein readings.

During the follow-up period, 40.4 percent of participants developed overall obesity and 41 percent developed abdominal obesity. The rates of CAC were higher in participants who for 20 or more years had overall obesity compared with those who never were obese—38.2 percent vs. 24.9 percent—and those with abdominal obesity compared with those who never were obese —39.3 percent vs. 24.7 percent.  

CAC progressed in 25.2 percent and 27.7 percent of those with more than 20 years of overall obesity and abdominal obesity, respectively, compared with 20.2 percent and 19.5 percent of those with no years of obesity.

Every year of overall or abdominal obesity starting in young adulthood was associated with an adjusted odds ratio (OR) of 1.04 for CAC progression. The OR for progression of CAC for those with more than 10-year duration of overall obesity compared those who never developed obesity was 1.99; for participants with abdominal obesity, the OR was 2.32.

“These findings suggest that the longer duration of exposure to excess adiposity as a result of the obesity epidemic and an earlier age at onset will have important implications on the future burden of coronary atherosclerosis and potentially on the rates of clinical cardiovascular disease in the United States,” they wrote.

In June, the AMA voted to designate obesity a disease, arguing that “recognizing obesity as a disease will help change the way the medical community tackles this complex issue that affects approximately one in three Americans.”

Reis and colleagues suggested that preventing obesity among young adults—or if not that, delaying its start—may reduce the risk and progression of coronary atherosclerosis over time.