15-year study shows strong link between fast food, obesity and insulin resistance

Researchers have shown a correlation between fast food, weight gain, and insulin resistance in what appears to be the first long-term study on this subject. The Coronary Artery Risk Development in Young Adults (CARDIA) study by Mark Pereira, Ph.D., assistant professor in epidemiology, University of Minnesota School of Public Health, and David Ludwig, M.D., Ph.D., director of the Obesity Program at Children’s Hospital Boston, reported that fast food increases the risk of obesity and type 2 diabetes. The results of this 15-year study will be published in the Jan. 1 issue of The Lancet.

Participants who consumed fast food two or more times a week gained approximately 10 more pounds and had twice as great increase in insulin resistance in the 15-year period than participants who consumed fast food less than once per week.

“Fast-food consumption has increased in the United States during the past three decades,” said Pereira. “While there have been many discussions about fast-food’s effects on obesity, this appears to be the first scientific, comprehensive long-term study to show a strong connection between fast-food consumption, obesity, and risk for type 2 diabetes.”

“The CARDIA study factored in and monitored lifestyle factors including television viewing, physical activity, alcohol consumption, and smoking, but determined that increase in body weight and insulin resistance from fast-food intake seemed to be largely independent of these other lifestyle factors,” said Ludwig.

Fast-food frequency was lowest for white women (about 1.3 times per week) compared with the other ethnic and gender groups (about twice a week). Frequency was higher in African-Americans than in whites and in men than in women for every examination year. Age- adjusted fast-food frequency was relatively stable over time among African-Americans but fell in those who were white.

This study of cardiovascular disease risk factor evolution included 3,031 young (age 18-30 years in 1985) African-American and white adults whose frequency of fast-food visits, changes in body weight and insulin resistance were monitored and measured for 15 years. This was a multi-center, population-based study with study centers in Birmingham, Ala., Chicago, Ill., Minneapolis, Minn., and Oakland, Calif.