higher protective effect among adolescents 10-19 years (OR 0.49; 95% CI 0.38, 0.63) compared to adults 20+ years (OR 0.77; 95% CI 0.66, 0.90) (Horta and de Lima 2019).

Based on cross-sectional studies, total dairy product (including milk, yogurt and cheese) consumption in children 2- 21 years is associated with a reduced risk of obesity (OR 0.66; 95% CI 0.48, 0.91) but not overweight (Babio et al. 2022). In a meta-analysis of 14 studies (11 cross-sectional and 3 cohort), regular consumption of _whole_ milk (compared to reduced fat milk) was associated with a lower risk of overweight and obesity among children 1-18 years (OR 0.61; 95% CI 0.52, 0.72) (Vanderhout et al. 2020).

High SSB intake is also associated with increased BMI in children 2-18 years, with a mean difference of 0.75 kg/m2 (95% CI 0.35, 1.15), higher waist circumference (WMD 2.35 cm; 95% CI, 1.34, 3.37; p = 0.016) and higher body fat percentage (WMD: 2.81; 95% CI 2.21–3.41; p < 0.001) (Abbasalizad Farhangi et al. 2022).

# Children 5+ years of age

Our search identified 16 SRM on the risk of malnutrition associated with dietary intake in older children, with four overlapping with children <5 years and one overlapping with adults (see **Table 6** ). As with children <5 years, there is evidence that low diet diversity among children 5-18 years across six LMICs is associated with increased risk of stunting (OR 1.43; 95% CI 1.08, 1.89), and wasting (OR 2.18; 95% CI 1.41, 3.36), but not thinness (Zeinalabedini et al. 2023). Low diet diversity is also associated with increased risk of low BMI-for-age (<-2 SD) in adolescents in Ethiopia (OR 1.95; 95% CI 1.31, 2.92) (Berhe et al. 2019). Low diet diversity increases the odds of anemia among adolescent girls in Ethiopia, with effect size estimates ranging from 1.35-2.81 (Berhe et al. 2022; Habtegiorgis et al. 2022; Endale et al. 2022). Based on two studies from Ethiopia, low diet diversity is also associated with increased risk of overweight and obesity (OR 2.26; 95% CI 1.28, 3.99) (Gezaw et al. 2023a).

Several SRM have summarized the evidence on the contribution of unhealthy diets, including SSB intake, to the growing burden of overweight and obesity in children 5-19 years. Higher adherence to an unhealthy dietary pattern (mainly represented by red and processed meat, confectionery and bakery items, full-fat dairy products, refined grains, desserts and candies) was associated with higher BMI (mean diff 0.57 kg/m2 (95% CI 0.51, 0.63) and waist circumference (mean diff 0.57 cm (95% CI 0.47, 0·67) in children and adolescents 7-19 years (Cunha et al. 2018). SSB consumption, in particular, has been shown to increase the odds of overweight and obesity, with an effect size of 1.2 in two very large meta-analyses (Jakobsen, Brader, and Bruun 2023; Poorolajal et al. 2020). As stated above for children <5 years, high SSB intake is associated with higher BMI, body fat percentage and waist circumference (Abbasalizad Farhangi et al. 2022). Other unhealthy foods associated with overweight/obesity in children and adolescents include fast food (OR 1.17; 95% CI 1.07, 1.28) and refined grains (OR 1.28; 95% CI 1.05, 1.56) (Jakobsen, Brader, and Bruun 2023).

Healthy dietary patterns (mostly composed of legumes, vegetables, fruit, fish, low-fat dairy products, nuts, olive oil and others) have been shown to be protective for overweight and obesity in children 7-19 years, associated with lower mean BMI (-0.41 kg/m2; 95% CI -0.46, -0.36) and waist circumference (-0.43 cm; 95% CI -0.52, -0.33) (Cunha et al. 2018). Milk and dairy product consumption are also associated with reduced risk of overweight and obesity in children of all ages, with effect sizes ranging from 0.54 to 0.87 (Babio et al. 2022; Vanderhout et al. 2020; W. Wang, Wu, and Zhang 2016).

# Adults

Our search identified 44 SRM articles that assessed the risk of overweight and obesity, T2DM or hypertension associated with dietary intake in adults (see **Table 7** ).

## **Nutrition outcomes**

Only one SRM was found that looked at a micronutrient-related outcome in adults. Haider et al. (2018) found that adult vegetarians had significantly lower serum ferritin concentration compared to non-vegetarians.

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