Kling 2016

Methods	Study design: Cluster‐randomised controlled trial – cross‐over Funding: “Supported by NIH Grant R01‐DK082580 and USDA National Institute for Food and Agriculture Grant 2011‐67001‐30117 Program A2121‐Childhood Obesity Prevention: Transdisciplinary Graduate Education and Training in Nutrition and Family Sciences”
Participants	Description: Children aged 3‐6 years enrolled in 3 childcare centres near University Park, Pennsylvania N (Randomised): 11 classrooms, 31 children Age: Overall mean = 4.4 years % Female: 49% SES and ethnicity: “Based on the 106 parents (88%) who provided family information, household incomes and education levels were above average: 69% of households had an annual income of above $50,000 and 92% of mothers and 90% of fathers had a Bachelor's degree or higher.” “The sample of children was 69% white, 21% Asian, 3% black or African American, and 7% of mixed or another race; 4% were of Hispanic or Latino origin.” Inclusion/exclusion criteria: Inclusion criteria: children had to be enrolled in participating childcare centres Exclusion criteria: children with an allergy or intolerance to the foods or milk being served Recruitment: “Children were recruited by giving letters to parents with 3‐ to 6‐year‐old children enrolled at three childcare centers near University Park, PA.” Recruitment rate: Unknown Region: Pennsylvania, USA
Interventions	Number of experimental conditions: 6 Number of participants (analysed): Overall = 120 Description of intervention: Across the 6 meals (groups), all foods and milk were served at 3 levels of portion size (100%, 150%, or 200% of reference amounts) and 2 levels of energy density (100% or 142%) and were consumed ad libitum” “The experimental meal consisted of chicken (grilled breast or breaded nuggets), macaroni and cheese, a green vegetable (broccoli or peas), applesauce, ketchup, and milk.” Duration: 6 weeks Number of contacts: 6 (1 meal/week) Setting: Preschool Modality: Face‐to‐face Interventionist: Teachers and undergraduate research assistants Integrity: No information provided Date of study: “enrolled in the study from May 2013 to July 2014.” Description of control: N/A
Outcomes	Outcome relating to children's fruit and vegetable consumption: Consumption of vegetables (grams): “To determine the amount consumed, all foods and beverages were weighed before and after the meal in a separate room out of the children's view. Food weights were recorded to the nearest 0.1 g using digital scales” Outcome relating to absolute costs/cost‐effectiveness of interventions: Not reported Outcome relating to reported adverse events: Not reported Length of follow‐up from baseline: 6 weeks Length of follow‐up post‐intervention: Immediately Subgroup analyses: None Loss to follow‐up: Overall: 8% (11/131) Analysis: Unknown if adjusted for clustering Sample size calculations performed
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	“The order of the six conditions was counterbalanced across classrooms using Latin squares, and classrooms were randomly assigned one of the condition sequences using a random number generator.”
Allocation concealment (selection bias)	Unclear risk	There is no information provided about allocation concealment and therefore it is unclear if allocation was concealed from those conducting the research.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	“Neither parents nor children were informed about the purpose of the study.” “During each meal, adults, including teachers and undergraduate research assistants who did not know the purpose of the study, were instructed to redirect conversations about food‐related topics to minimize peer influence on children's lunch intake.”
Blinding of outcome assessment (detection bias) All outcomes	Low risk	“During each meal, adults, including teachers and undergraduate research assistants who did not know the purpose of the study” low risk. Researchers who weighed all food and drink before and after the meal. Researchers were blinded to the purpose of the study.
Incomplete outcome data (attrition bias) All outcomes	Low risk	”A total of 131 children from 11 classrooms at the 3 childcare centers were enrolled in the study from May 2013 to July 2014. Eleven children were excluded from the analysis because they were absent for 3 or more of the 6 experimental meals. Thus, intake data was analyzed for 120 children (61 boys and 59 girls).” No attrition is reported.
Selective reporting (reporting bias)	Low risk	All proposed outcomes in trial registry are reported.
Other bias	Low risk	No other bias was identified