Background

The goal of this systematic review was to determine whether sedentary behavior is associated with measures of dietary intake or body weight. Sedentary behavior, which refers to any waking activity predominantly done while in a sitting or reclining posture, is gaining considerable public health interest as a chronic disease risk factor and therefore a potential area for interventions to target, with reducing screen time often a focus. The US population has become increasingly sedentary,¹ with the daily hours of screen time exposure becoming a serious public health concern due to its potential negative influence on dietary and weight outcomes.

Conclusion statement

Moderate and consistent evidence from prospective studies exists that associates increased
TV viewing in childhood and adolescence with higher body weight and increased incidence of
overweight and obesity in adulthood.

2015 DGAC Grade: Moderate

Moderate evidence from prospective studies suggests no association between sedentary
behavior in adulthood and change in body weight, body composition or incidence of
overweight or obesity in adulthood.

2015 DGAC Grade: Moderate

Insufficient evidence exists to address the association between sedentary behavior and
dietary intake in adults.

2015 DGAC Grade: Not Assignable

Methods

Literature searches were conducted using PubMed, Embase and Cochrane databases to identify studies that evaluated the association between sedentary behavior and dietary intake and body weight. Studies that met the following criteria were included in the review: randomized controlled studies (RCTs) or non-randomized controlled studies, prospective cohort studies; intervention studies with a dropout rate 20% or less and a differential dropout rate of 15% or less between groups; human subjects aged 19 years and older (except for longitudinal studies into adulthood); subjects who were healthy or at elevated chronic disease risk; populations from countries with a high or very high 2012 Human Development Index. Included studies were published in English in peer-reviewed journals from January 2004 to January 2014. The intervention or exposure was sedentary behaviors, including recreational and occupational, and screen time. The outcome was measures of dietary intake including diet quality, foods, food groups, macronutrient intakes or proportions and incidence of obesity, overweight and measures of body weight, body mass index (BMI) and body composition, including waist circumference. Acute feeding studies and studies conducted in pregnant and postpartum women were excluded.

Data from each included article were extracted, and risk of bias was assessed. The evidence was qualitatively synthesized, a conclusion statement was developed and the strength of the evidence (grade) was assessed using pre-established criteria including evaluation of the quality and risk of bias, quantity, consistency, magnitude of effect and generalizability of available evidence.

Findings

• This evidence review included 23 studies from 18 prospective cohorts that examined the relationship between sedentary behavior and body weight status in adults
• Increasing levels of TV viewing during childhood and adolescence predicted higher BMI and increased incidence of overweight and obesity in adulthood
• The lack of association between adult sedentary behavior (TV viewing, commute time or composite measures of sedentary behavior) and body weight change or body weight status are mostly consistent, despite methodological differences in measurement of sedentary behavior
• Among two studies that assessed the relationship between sedentary behavior in adulthood and dietary intake, one study found an association between TV viewing and lower compliance with recommended dietary guidance. The other study found that more TV viewing was associated with greater intake of calories from fat, but not total calories or calories from sweets.
• Methodological approaches differed with regard to population and cohort size, types of sedentary behavior considered and time frames studied. Only one study directly measured sedentary behavior, and few studies adjusted analysis for energy intake.
• The majority of studies were conducted in Caucasian populations; therefore, diverse ethnic and racial groups were underrepresented.

References

1. Owen N, Healy GN, Matthews CE, Dunstan DW. Too much sitting: the population health science of sedentary behavior. Exerc Sport Sci Rev. 2010;38(3):105-13. PMID: 20577058. http://www.ncbi.nlm.nih.gov/pubmed/20577058 (less)