Wednesday, December 17, 2008

Watching TV makes you fat

Seriously, it does. (the full text of this one is available)

Television, Physical Activity, Diet, and Body Weight Status: the ARIC Cohort

Television (TV) watching is the most common leisure activity in the United States. Few studies of adults have described the relationship between TV and health behaviors such as physical activity, diet, and body weight status.

Extant data from the Atherosclerosis Risk in Communities (ARIC) Study were analyzed to assess the association of TV with physical activity, diet, and body mass index (BMI) among 15,574 adults at baseline (1986-89) and 12,678 adults six years later. Television, physical activity, and diet were collected with questionnaires and BMI was measured at both time points. Based on baseline TV exposure, adults were categorized into high, medium, and low TV exposure. Linear and logistic regression models were adjusted for gender, age, race-center, smoking, education, and general health.

Relative to participants who had low TV exposure, those with high TV exposure were more likely to be less physically active and have a poorer dietary profile at baseline and six-years later. Participants with high TV exposure at baseline had a 40% and 31% and greater odds of being considered insufficiently active at baseline (1.40, 95% CI 1.26, 1.55), and six years later (1.31, 95% CI 1.18, 1.46). At baseline, high TV exposure was also associated with a 20% to 30% greater odds of being above the median for servings of salty snacks (1.37, 95% CI 1.24, 1.51), sweets (1.26, 95% CI 1.15, 1.38), and sweetened drinks (1.29, 95% CI 1.17, 1.42), and below the median for fruit and vegetable servings (1.36, 95% CI 1.24, 1.50). Higher TV exposure was also cross-sectionally associated with a greater odds for being overweight or obese (1.43, 95% CI 1.29, 1.58). Similar associations were observed between baseline TV exposure and six-year physical activity and diet, but were not observed with BMI after six years follow-up.

These results support the hypothesis that time spent watching TV is associated with deleterious effects on physical activity, diet, and BMI.


Son of Grok said...

Chris, do you think this is more correlation than causation? I tend to think so.

The SoG

Chris said...


definitely correlation / association not causation. It is not the TV watchgin itself that is to blame. TV is a distraction that stops you activity. (would Grok watch much TV? Or would be be sleeping in the dark, walking, playing, dancing, hunting, walking?)

Watching lots of TV tends to mean that people are spending a lot of time on their behinds instead of being active.

I'd also guess that the more people watch TV the less careful they are about diet. this willsound snobby, but it tends to be the less well educated etc that watch the most TV.

I think there is also something about light. TV is all part of this thing we have about not getting enough dark.