Sonneville K R, Gortmaker S L
Department of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA.
Int J Obes (Lond). 2008 Dec;32 Suppl 6:S19-27. doi: 10.1038/ijo.2008.203.
To estimate total energy intake and the energy gap-the daily imbalance between energy intake and expenditure-associated with discretionary behaviors of adolescents, namely their leisure active behaviors (playing or participating in sports and heavy chores), leisure sedentary behaviors (television (TV) viewing and playing video and computer games), productive sedentary behaviors (reading or doing homework).
Prospective observational study.
A total of 538 students (mean age at baseline=11.7 years) from public schools in the Boston area studied prospectively from the fall of 1995 to the spring of 1997.
Anthropometric assessment including height and weight, dietary assessment using a youth food frequency questionnaire and measures of TV, video, reading/doing homework and youth physical activity.
We estimate the change in total energy intake for each hour change in discretionary activity using regression methods. A 1-h increase in watching TV is associated with a 106 kcal h(-1) increase in total energy intake (95% confidence interval (CI): 61-150 kcal day(-1)). A similar change of 92 kcal h(-1) (95% CI: 37-147 kcal day(-1)) is seen with playing video and computer games. The change in energy intake associated with an hour change in physical activity is 292 kcal h(-1) (95% CI: 262-321 kcal day(-1)). No significant change is associated with reading/doing homework. Assuming that typical energy expenditures are associated with these behaviors, reading/doing homework appears to be an 'energy neutral' activity, whereas watching TV and playing video and computer games is associated with an energy surplus. If we assume that physical activity levels are moderate (3.5 METs), then this is also an energy surplus activity. If physical activity is assumed to be vigorous for the entire time allotted (>6.0 METs), an energy deficit could be achieved. We validated these estimates by calculating regressions predicting change in weight. Results indicate that each hour increase in TV viewing is associated with a weight increase of 0.38 kg (95% CI: 0.17-0.59 kg), with no significant associations for the other behaviors. A model with change in BMI as the dependent variable produced similar results.
Watching TV is an activity associated with a daily energy surplus. Although physical activity is thought of as an energy deficit activity, our estimates do not support this hypothesis. Reading/doing homework is the only discretionary activity examined which appears to be clearly energy neutral. The differential impacts of these discretionary behaviors on energy intake and the energy gap are discussed in relation to food-related advertisements aimed at children and adolescents.
评估青少年的总能量摄入量以及能量差距（即能量摄入与能量消耗之间的每日不平衡），该能量差距与青少年的随意性行为相关，即他们的休闲活动行为（玩耍或参加体育运动以及繁重家务）、休闲久坐行为（看电视、玩电子游戏和电脑游戏）、学习久坐行为（阅读或做作业）。
前瞻性观察研究。
1995年秋季至1997年春季对波士顿地区公立学校的538名学生（基线时平均年龄 = 11.7岁）进行前瞻性研究。
人体测量评估，包括身高和体重；使用青少年食物频率问卷进行饮食评估；以及对电视、电子游戏、阅读/做作业和青少年身体活动的测量。
我们使用回归方法估计随意活动每变化1小时时总能量摄入的变化。看电视每增加1小时，总能量摄入增加106千卡/小时（95%置信区间（CI）：61 - 150千卡/天）。玩电子游戏和电脑游戏也有类似的变化，为92千卡/小时（95%CI：37 - 147千卡/天）。身体活动每变化1小时，能量摄入变化为292千卡/小时（95%CI：262 - 321千卡/天）。阅读/做作业未发现显著变化。假设这些行为与典型的能量消耗相关，阅读/做作业似乎是一种“能量中性”活动，而看电视、玩电子游戏和电脑游戏与能量过剩相关。如果我们假设身体活动水平为中等（3.5代谢当量），那么这也是一种能量过剩活动。如果假设在分配的整个时间内身体活动剧烈（>6.0代谢当量），则可以实现能量 deficit。我们通过计算预测体重变化的回归来验证这些估计。结果表明，看电视每增加1小时，体重增加0.38千克（95%CI：0.17 - 0.59千克），其他行为未发现显著关联。以BMI变化作为因变量的模型产生了类似的结果。
看电视是一种与每日能量过剩相关的活动。尽管身体活动被认为是一种能量 deficit 活动，但我们的估计不支持这一假设。阅读/做作业是所研究的唯一一种似乎明显能量中性的随意活动。讨论了这些随意性行为对能量摄入和能量差距的不同影响与针对儿童和青少年的食品相关广告的关系。
