The common daily activity that ruins health and contributes to chronic disease

People spend an inordinate amount of time watching television. It’s the most frequently reported daily activity aside from work and sleep. Americans watch nearly 6 hours of TV and videos each day, according to Nielson. In other countries, these numbers are equally concerning—Australians spend 50% and Europeans spend 40% of their free time watching television. 

All these sedentary hours take their toll on health in various ways.

Chronic disease and death

In a literature review and meta-analysis of cohort studies published in JAMA, researchers examined the association between TV viewing and type 2 diabetes, fatal/nonfatal heart disease, and all-cause mortality. Their results were disheartening (literally). 

The studies were high powered, with thousands of participants. For every 2 hours of TV watching per day, the relative risk increased 20% for type 2 diabetes, 15% for cardiovascular disease, and 13% for premature mortality. Watching more than 3 hours per day increased the risk of mortality, while the correlations between time spent viewing TV and type 2 diabetes risk and cardiovascular disease were linear. 

For every 2 hours of TV viewing, the estimated absolute risk differences for type 2 diabetes was 176 cases per 100,000 persons per year, 38 cases of fatal cardiovascular disease per year, and 104 deaths for all-cause mortality per year.

Many prospective studies by other researchers have shown that TV viewing is linked with biological risk factors including obesity, adverse lipid levels, and clustered cardiovascular risk.

“The message is simple: Cutting back on TV watching can significantly reduce risk of type 2 diabetes, heart disease, and premature mortality,” said senior author Frank Hu, MD, MPH, professor of nutrition and epidemiology, Harvard School of Public Health, Boston, MA. “We should not only promote increasing physical activity levels but also reduce sedentary behaviors, especially prolonged TV watching.”

While watching television, people often munch on food and are also exposed to advertising for unhealthy foods. The authors took these factors into consideration and found that there was a small attenuation in risk for type 2 diabetes but not in risk for heart disease or all-cause mortality after adjusting for dietary variables.

“Beyond altering energy expenditure by displacing time spent on physical activities, TV viewing is associated with unhealthy eating (eg, higher intake of fried foods, processed meat, and sugar-sweetened beverages and lower intake of fruits, vegetables, and whole grains) in both children and adults,” the authors reflected.

Obesity and hypertension

Results from a cross-sectional study of 14,189 adults published in the European Journal of Clinical Nutrition indicated “that time spent participating in vigorous recreational physical activity and television viewing, an indicator of a sedentary lifestyle, are associated with obesity and markers of CVD disease risk independent of total reported physical activity.” 

After accounting for covariates including age, alcohol use, smoking, antihypertensive medication use, and physical activity, the researchers found that adults who participated in more than 1 hour of vigorous activity per week and who watched less than 2 hours of television per day, the adjusted mean body mass index was 1.92 kg/m2 less in women and 1.44 kg/m2 less in men compared with those who participated in no vigorous activity and watched more than 4 hours of television per day (P<0.001).

In a similar analysis, average diastolic blood pressure measures also improved in those who watched less TV and engaged in vigorous physical activity, with a 3.6 mmHg drop in men (P<0.001) and a 2.7 mmHg drop in women (P=0.001).

Interventions

Excessive time spent consuming television—and gaming—starts early in the lives of average Americans. Fortunately, reducing time in front of the TV can curb obesity measures, according to results of randomized trials.

For instance, in a randomized controlled school-based trial published in JAMA, researchers found improvement in health patterns in 198 third- and fourth-grade students exposed to curriculum-based measures to lessen media consumption.

The authors advised that reducing media utilization “may be a promising, population-based approach to help prevent childhood obesity.”

Bottom line

Compared with the average American, it’s unlikely that the average physician has time to watch almost 6 hours of TV or videos each day. But, according to the research, even a couple hours of sedentary time in front of the idiot box may be too much. In addition to curbing television consumption, it may be a good idea to participate in exercise or constructive hobbies rather than binge-watch movies and shows on Netflix, Hulu, Amazon Prime, and all the rest.