A few broad conclusions emerged from the study. First, watching more than 2 hours of television per day was associated with having a high BMI and being overweight or obese in both men and women. In general, across all socioeconomic and demographic groups analyzed, with the exception of racial and ethnic groups, significantly higher percentages of adults who watched more than 2 hours of television per day were overweight compared with adults who watched less than 1 hour of television per day. Among racial and ethnic groups, television-viewing status varied significantly only between groups of white adults. Small sample sizes may explain the lack of differences among the other three racial and ethnic groups. Only a small percentage of African Americans, Hispanics, and "other races" watched less than 1 hour of television per day. The small sample sizes resulted in large standard errors. Also, some of the racial and ethnic categories used in this study were not homogeneous. For example, the Hispanic category included Mexican, Mexican American, Cuban, Puerto Rican, and other Hispanic; and the Other category included American Indians, Alaska Natives, Pacific Islanders, and Asians.
A high percentage of adults aged 50 or older watched more than 2 hours of television per day. Retirement may explain the more sedentary lifestyle, especially among adults aged 65 or older. Low household income, low level of education, and not being employed were associated with more adults watching more than 2 hours of television. More African American adults than white adults watched more than 2 hours of television. Having 4 years of college education or being employed was associated with a relatively low percentage of adults watching more than 2 hours of television per day. Similar findings were noted by Sidney et al (15
). Using cross-sectional data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study, they found that African Americans watched more hours of television per day than whites, and the number of hours of television viewed was inversely associated with education and income. Also, compared with those who watched less than 1 hour of television, the study found that those who watched more than 4 hours of television per day had a higher prevalence of obesity in all race and sex groups.
A significantly higher percentage of not-employed adults compared with employed adults watched more than 2 hours of television per day, indicating more available leisure time. However, among not-employed adults who were keeping house, a low percentage watched more than 2 hours of television per day, and a small percentage of them were overweight. Very likely, these adults had less leisure time available and were also physically active. Standing or walking around the home for 2 hours daily is associated with a 9% reduction in obesity in women (14
Second, adults who had health conditions such as diabetes, hypertension, heart disease, or high blood cholesterol watched more than 2 hours of television per day, and a high percentage of them were also overweight. A small sample size (5.8% of the total population) may be the reason for not observing differences among adults with diabetes. Although the cross-sectional data provided by CSFII cannot be used to show cause and effect, the results show an association between health conditions, television viewing, and overweight status.
Many research studies have shown positive associations between prolonged television viewing and obesity and health conditions. Using data from a large prospective cohort study, Hu et al observed that prolonged television watching was positively associated with an increased risk of obesity and type 2 diabetes in men and women (13
). From their study on women, they concluded that watching fewer than 10 hours of television per week and walking briskly for 30 minutes or more per day would prevent new cases of obesity in 30% of their cohort and prevent new cases of diabetes in 43% of the same cohort (14
). Kronenberg et al (10
) observed significant positive associations between television watching and obesity-related anthropometric measurements such as BMI, waist girth, waist–hip ratio, subscapular and triceps skinfold thickness, and atherosclerosis risk factors. Hubert et al (27
) used a cross-sectional survey of Latino women aged 18 to 64 and found that watching television regularly was one of the significant factors associated with higher BMI (27
). Fung et al, in a long-term study from 1986 to 1994 of 468 healthy male health professionals, found a positive association between television viewing and leptin levels and low-density lipoprotein cholesterol and an inverse association between television viewing and high-density lipoprotein cholesterol and apolipoprotein A1 (28
Third, after adjusting for socioeconomic and demographic variables, adults who watched more than 2 hours of television per day consumed 137 calories more than adults who watched less than 1 hour of television per day. Assuming that the energy intakes and expenditures remain constant throughout the year for the adults who watch more than 2 hours of television per day and that they consume more calories than they expend, these 137 excess calories per day would translate into a gain of 14.3 pounds per year.
The CSFII collects information on the time of day each food or beverage is consumed, but it does not collect information on the time of day that television is watched. Therefore, it is not possible to provide direct evidence from this study that people surveyed ate while watching television or that watching television contributed to increased energy intakes. This is a limitation of the study. However, other studies have shown that people consume more food or energy while watching television. Gore et al reported that snacking (but not necessarily eating meals) while watching television was associated with increased total energy and energy from fat in women (20
In this study, adults who watched more than 2 hours of television per day had significantly higher energy intakes at supper (46 more calories) and from snacks (61 more calories) and obtained a significantly higher percentage of energy from added sugars than those who watched less than 1 hour of television. Diets high in added sugars have been associated with poor nutritional quality (29
). Adults who watched more than 2 hours of television per day also consumed more added sugar through regular soft drinks (81 more grams), the top source of added sugars in the United States (29
) and ate more energy-rich snack-type foods such as cakes, cookies, corn chips, fried potatoes, and grain mixtures such as pizza. Snacking while watching television has been associated with increased daily energy intake and increased total fat calories (20
The underlying causes of overweight and obesity are multidimensional. However, individuals from all socioeconomic backgrounds would benefit from reducing their television- or video-viewing time or time spent in similar sedentary activities. Instead of watching television, they may spend leisure time to increase their physical activity levels. People who are retired, disabled, or have health conditions may choose to do light- or moderate-intensity activities such as walking, stretching, and doing household chores. Others who are not limited by health conditions may engage in more vigorous or high-intensity physical activities.
Also, adults should be cognizant of the fact that eating while watching television could potentially increase their energy intakes substantially and may lead to positive energy balance. Therefore, adults should refrain from consuming energy-rich foods and beverages while watching television. Health interventions aimed at preventing or treating obesity should emphasize reducing time spent watching television or doing similar sedentary activities.
A lack of access to safe physical activity sites such as health spas, gyms, parks, walking trails, and swimming pools should not be a limiting factor for exercise or physical activity. A wide range of sports equipment such as treadmills, weight machines, and stationary bikes available in the market can be used in homes. Adults may also choose an exercise they may enjoy doing while watching television.