Background 

The majority of Americans consume meals outside of the home one or more times per week. The 2010 DGAC concluded that “strong and consistent evidence indicates that children and adults who eat fast food are at increased risk of weight gain, overweight and obesity.” With this relationship as a foundation, this review provided an update and expanded the “eating out” topic. Specifically, the fast-food category was broadened to capture other types of eating out venues (e.g., quick serve, casual, formal restaurants, and grocery store takeout). Terminology used to define the exposure was modified from “eating out” to the broader term “eating out and take-away meals” to reflect the inclusion of meals eaten out at a broader array of restaurant venues, as well as takeout or ready-to-eat foods or meals purchased and consumed either away from or in the home. The population of interest remained healthy individuals ages two years and older.

Conclusion statement 

Among adults, moderate evidence from prospective cohort studies in populations ages 40 years or younger at baseline indicates higher frequency of fast-food consumption is associated with higher body weight, body mass index (BMI) and risk for obesity. 

2015 DGAC Grade: Moderate 

Among children, limited evidence from prospective cohort studies in populations ages eight to 16 years at baseline suggests that higher frequency of fast-food consumption is associated with increased adiposity; BMI Z-score; or risk of obesity during childhood, adolescence and during the transition from adolescence into adulthood. 

2015 DGAC Grade: Limited 

Insufficient evidence is available to assess the relationship between frequency of other types of restaurant and takeout meals and body weight outcomes in children and adults. 

2015 DGAC Grade: Not assignable

Methods 

Literature searches were conducted using PubMed, Embase, Cochrane, Scopus, Web of Science, and CINAHL databases to identify studies published in English in peer-reviewed journals from January 2010 to present. Included studies met the following inclusion and exclusion criteria established a priori to the review: randomized controlled trials (RCT), prospective cohort studies, crossover trials, non-randomized controlled trials; human subjects aged two years and older who were healthy or at elevated chronic disease risk; studies conducted in high or very highly developed countries (Human Development Index, 2013); frequency of eating out or take-away food meals on weight outcomes including obesity, overweight, body mass index (BMI), waist circumference, body weight, percent body fat change; child growth indices (weight-for-age, length/stature-for-age, weight for stature, BMIfor-age, BMI Z-score). 

The search results were combined with the results of a similar search used for the 2010 Systematic Reviews of the Individual Diet and Physical Activity Behavior Change Subcommittee, 2015 DGAC 6 Archived from www.NEL.gov on March 21, 2017 DGAC. The 2010 DGAC search included studies from January 2000 to January 2010 that met the following inclusion and exclusion criteria established a priori to the review: systematic reviews and meta-analysis, RCTs or clinical controlled studies, large non-randomized observational studies, cohort, case-control studies; human subjects aged two years and older who were healthy or at elevated chronic disease risk. 

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

• In children, seven prospective cohort studies examined the relationship between frequency of fast-food meals (six studies), or consumption of other types of meals and anthropometric outcomes and overall found mixed results:
  • Six studies examined fast-food meals: Three studies indicated increased fast food intake, particularly more than twice per week, was associated with increased risk of obesity, BMI/BMI Z-score or body fat; two found no association; and one found no association in boys and a negative association in girls
  • Two studies looked at a variety of non-fast-food meals away from home, using varying definitions of food establishments and meal types, and reported mixed findings for a relationship with weight-related outcomes. 
• In adolescents transitioning to adulthood, one study found high baseline frequency of fast-food intake was associated with increased BMI Z-scores at five-year follow-up
• In adults, evidence consistently demonstrated a relationship between increased frequency of fast-food meal consumption and weight outcomes:
  • Five prospective cohort studies (three cohorts) reported that increased intake of meals from fast-food locations, or intake exceeding once per week, was associated with higher weight gain, BMI and risk for obesity 
• Evidence related to the association between frequency of meals from other types of restaurants and intake of all takeout meals and weight is limited, but indicates traditional restaurant meal frequency may not be associated with weight outcomes: 
  • Two studies examined total meals away from home or meal types eaten away from home, which came from both fast-food and restaurant locations, and reported frequency was associated with increased weight outcomes for most meal types 
  • Two studies from the same cohort found no relationship between frequency of meals from restaurants (non-fast-food establishments), and weight-related outcomes.
• Data are sparse regarding meal composition and in studies in young children or older adults. Hispanic/Latino and Asian populations are poorly represented in this body of literature.

Limitations

• Methods used to define and measure the exposure varied between studies and did not capture the full range of eating out or takeout opportunities
• Representation of Hispanic/Latino and Asian populations, young children and older adults was poor
• Several studies in children used reported height and weight for outcome assessment, and BMI Z-scores were not consistently used
• There was little or no information on the composition of meals and the relationship between meal composition and outcomes 
• Few studies controlled for total energy intake