Dramatic Decreases in BMI Percentiles, but Valid Conclusions Can Only Come From Valid Analyses

Fourth-Grade Cooking and Physical Activity Intervention Reveals Associations With Cooking Experience and Sex

OBJECTIVE

Examine the impact of Fuel for Fun: Cooking with Kids Plus Parents and Play (FFF) on children's culinary self-efficacy, attitude, fruit and vegetable (FV) preferences, physical activity (PA), and body mass index.

DESIGN

Randomized controlled trial.

SETTING

Eight elementary schools in 2 Northern Colorado districts.

PARTICIPANTS

Fourth-grade students; 7-month interventions: school (S.FFF)-theory-based cooking + tasting lessons, active recess, lesson-driven cafeteria promotions; or school + family (S+F.FFF) with added family nights and home activities.

MAIN OUTCOME MEASURE(S)

Cooking self-efficacy and attitudes, FV preferences, PA, and measured height/weight.

ANALYSIS

Individual outcomes nested by classroom, school, and district and assessed > 12 months with repeated measures controlled by sex and baseline cooking experience, with a significance level of P < 0.05.

RESULTS

The sample included 1,428 youth, 38 teachers, 4 cohorts, 50% boys, 75% White, and 15% Hispanic. No intervention effect was observed. Those who cooked retained higher self-efficacy, attitude, and FV preferences (P < 0.001). Girls reported higher self-efficacy and attitude than boys. Moderate-to-vigorous PA and metabolic equivalent minutes increased for all students; boys retained higher levels (P < 0.001). Body mass index percentile remained stable.

CONCLUSIONS AND IMPLICATIONS

Cooking and sex were associated with all outcome measures and should be considered for intervention tailoring. Treatment impacts were not evident nesting by classroom, school, and district. Accurate assessment of school-based interventions requires rejecting student independence from group assignment assumptions.

Childhood obesity intervention studies: A narrative review and guide for investigators, authors, editors, reviewers, journalists, and readers to guard against exaggerated effectiveness claims

Being able to draw accurate conclusions from childhood obesity trials is important to make advances in reversing the obesity epidemic. However, obesity research sometimes is not conducted or reported to appropriate scientific standards. To constructively draw attention to this issue, we present 10 errors that are commonly committed, illustrate each error with examples from the childhood obesity literature, and follow with suggestions on how to avoid these errors. These errors are as follows: using self-reported outcomes and teaching to the test; foregoing control groups and risking regression to the mean creating differences over time; changing the goal posts; ignoring clustering in studies that randomize groups of children; following the forking paths, subsetting, p-hacking, and data dredging; basing conclusions on tests for significant differences from baseline; equating "no statistically significant difference" with "equally effective"; ignoring intervention study results in favor of observational analyses; using one-sided testing for statistical significance; and stating that effects are clinically significant even though they are not statistically significant. We hope that compiling these errors in one article will serve as the beginning of a checklist to support fidelity in conducting, analyzing, and reporting childhood obesity research.