The more hours young adults spend watching television each day, the greater the likelihood that they’ll have a higher body mass index and bigger waist circumference, according to a 15-year analysis by the University of Pittsburgh Graduate School of Public Health.
The association was not seen in later years, suggesting that young adulthood is an important time to intervene and promote less television viewing.
Lead author Anthony Fabio, Ph.D., M.P.H., assistant professor of epidemiology at Pitt Public Health, said:
“We were quite surprised to find that television viewing was associated with subsequent obesity for young adults, but not for the middle-aged. This suggests that middle-aged adults may differ from young adults in how they respond to the influence of TV viewing."
Dr. Fabio and his colleagues analyzed data from 3,269 adults recruited from Birmingham, Ala., Chicago, Minneapolis, and Oakland, Calif., who participated in the Coronary Artery Risk Development in Young Adults (CARDIA) Study.
For 15 years starting in 1990, the participants reported their television viewing habits and had their waist circumference measured and their body mass index (a measure of weight and height that can indicate obesity) calculated every five years.
The more time participants spent watching television when they were approximately 30 years old, the more likely they were to be obese five years later, compared to their peers who spent less time in front of the television. The team did not have data on younger ages.
There are many posible reasons for the association, including that young adults may be more likely to snack during television viewing and consume unhealthy food due to their greater susceptibility to the seduction of junk food advertising on television. In support of that hypothesis, the CARDIA study also found that participants were more likely to eat healthier foods as they aged.
A lower family income and higher rates of smoking and drinking also were associated with more time spent watching television.
Chung-Yu Chen, Mark A. Pereira, Kevin H. Kim, Darin Erickson, David R. Jacobs, Janice C. Zgibor, Tammy Chung, Stephen Sidney, Carlos Iribarren, Anthony Fabio Fifteen-Year Prospective Analysis of Television Viewing and Adiposity in African American and Caucasian Men and Women SAGE Open Aug 2015, 5 (3) DOI: 10.1177/2158244015600480