Table 1 Characteristics extracted from the 24 included studies: BS (Breakfast skippers), BE (Breakfast eaters), CS (Cross-Sectional), LG (Longitudinal), y (years), m (months), FFQ (Food Frequency Questionnaire), WFR (Weigh food record), SES (Socioeconomic status), PA (Physical Activity), AM (Anthropometric measures), − (not reported)
Author, Year | Country | Age and Number of Participants | Study Design | Participants in Study | Dietary Assessment Tool | Confounding Factors Identified |
|---|---|---|---|---|---|---|
8 studies on Diet Quality | ||||||
 Richardson et al. 2015 [39] | USA | 18–44 y, N = 101 | CS | Women who had a child up to age 5 | 24-h Dietary recalls | SES, AM |
 Ferranti et al. 2013 [10] | USA | Mean age 48 y, N = 433 | LG (5 y follow up) | University and health center employees | FFQ | SES, PA, AM, |
 Isasi et al. 2015 [40] | USA | 18–74 y, N = 3141 | LG (9 m follow up) | Hispanic/Latino males and females | 24-h Dietary recalls | SES, PA, AM |
 El Ansari et al. 2015 [41] | Egypt | 16–30 y, N = 1483 | CS | Undergraduate students males and females | FFQ | SES, PA, AM |
 Valipour et al. 2017 [42] | Iran | 28–45 years old, N = 2134 | CS | General Adults | FFQ | SES, PA, AM |
 Fowles et al. 2012 [43] | USA | Mean age 24.7 y, N = 71 | CS | Low income pregnant women | 24-h Dietary recalls | SES, AM |
 Fowles et al. 2011 [44] | USA | Mean age 25 y, N = 118 | CS | Low income pregnant women | 24-h Dietary recalls | SES, AM |
 Widaman et al. 2016 [45] | USA | Mean Age 25.1, N = 35 (BS) Mean Age 24.1, N = 40 (BE) | CS | Female habitual breakfast eaters and breakfast skippers | 24-h Dietary recalls | PA, AM |
16 studies on Food Intake and Frequency of Consumption | ||||||
 Vidal et al. 2018 [1] | Peru | Mean Age: 19 y, N = 272 | CS | Undergraduate students | Block fat screener | SES |
 Nastaskin et al. 2015 [46] | Canada | Mean age: 20 y, N = 113 | CS | Students | Block fat screener/ Block sodium screener | SES, AM |
 Pettit et al. 2011 [47] | USA | 18–24 y, N = 78 | CS | Undergraduate students | Energy drink intake questions | SES |
 Mikolajczyk et al. 2009 [34] | Germany, Poland, Bulgaria | Mean age: 20 y, N = 1201 | CS | Fist year undergraduate students | FFQ | – |
 Errisuriz et al. 2016 [48] | USA | Mean age: 18.9 y, N = 433 | CS | Freshman students | Food and beverage frequency questions | SES, AM |
 El Ansari et al. 2014 [15] | UK | Mean age: 24.9 y, N = 2699 | CS | Students | FFQ | – |
 Ng et al. 2003 [49] | USA | Mean age: 40 y, N = 6620 | CS | Working adults | Block Fat Screener/ Alcohol frequency questions | SES, PA |
 Barrington et al. 2012 [37] | USA | 18–65 y, N = 357 | CS | Working adults | Single-item question for fast food intake/ 5-A-Day fruit & vegetable assessment tool | SES, PA, AM |
 Grossniklaus et al. 2010 [50] | USA | Mean age: 41.3 y, N = 64 | CS | Working adults | 3-day WFR | SES, AM |
 Papier et al. 2015 [16] | Australia | Mean Age 21.2 y, N = 397 | CS | Students | FFQ | SES, PA, AM |
 Roohafza et al. 2013 [35] | Iran | Mean age: 38.4–39.5 y, N = 9549 | CS | General adults | FFQ | SES, PA, AM |
 Gonzalez et al. 2013 [51] | Puerto Rico | 21–30 y, N = 186 | CS | First and second year students | Alcohol frequency questions | SES |
 Tseng et al. 2011 [36] | USA | Mean age 43.9 y, N = 426 | CS | Premenopausal women | 48- h Dietary recalls | SES |
 Hinote et al. 2009 [33] | 8 post-Soviet republics | > 18 y, N = 10,454 | CS | General adults | Questions about frequency of consumption | SES |
 Hwang et al. 2010 [52] | Korea | Mean age: 23.7 y, N = 570 | CS | Vietnamese female marriage immigrants | 1-day Dietary recalls | SES, PA, AM |
 Wardle et al. 2000 [53] | UK | Mean Age: 36.29 y, N = 58 | CS | Staff of a store | 24-h Dietary recalls | SES, AM |