Can we estimate the causal effects of diet and sedentary behavior on schoolchildren’s overweight/obesity from observational studies?

Aim: To investigate the causal impact of diet and sedentary behavior on Brazilian schoolchildren’s overweight/obesity using data from observational studies. Methods: Annual cross-sectional nutritional surveys over 2013–2015 period, with 26,712 children old 7–12 years in Florianópolis, Brazil, provided for this analysis. The applied an online previous-day recall questionnaire food intake physical/sedentary activities. Outcome measures were overweight/obesity, whereas exposure variables daily frequencies consuming sugary drinks ultra-processed foods, total number dietary items consumed activities per day, breakfast, mid-morning snacks, lunch, afternoon snack, dinner, evening snack. Control included child age, sex, family income, school shift, survey year, day week refers to, metabolic equivalents (METs) physical (PAs), quality PA reports. Causal effects estimated by augmented inverse probability weighting. Results: Daily consumption drinks, eating ten or more engaging three behaviors significantly increased odds ratios (ORs) being overweight/obese range 3–24% compared to reference, 95% confidence intervals 1–32%. Among 19 ORs P-value ≤ 0.05, only 3 exceeded 10%. Conclusions: Under certain conditions, not uncommon large-scale monitoring surveillance studies, it is possible evaluate overweight/obesity. sugar-sweetened beverages, skipping overweight/obese.