healthy and unhealthy dietary patterns. Intake of ASF was used to assess risk of micronutrient deficiency and anemia during pregnancy. There were no studies found for LMICs that used a common diet metric to look at both nutrient inadequacies and NCD-related complications during pregnancy.

**Diet diversity was also a common and consistent measure of diet quality for children,** with studies from LMICs focused largely on the association of diet diversity with undernutrition outcomes, including stunting, wasting and anemia. No SRM was found that looked at diet diversity or consumption of meat, fish or eggs in relation to young child overweight and obesity. While several SRM assessed the risk of overweight and obesity with SSB intake in children <5 years, no other SRM with studies from LMICs was found for this age group that looked at nutrition or health outcomes associated with energy-dense and nutrient-poor foods, including UPF. In older children 5-19 years, various dietary exposures, including specific food groups (e.g. dairy, meat, SSB) and food patterns (e.g. diet diversity, unhealthy dietary pattern, fast food) were assessed in relation to risk of overweight and obesity.

**Diets for adults** – the mapping of evidence from meta-analyses of dietary risk factors for nutrition and health outcomes in adults in LMICs shows a wide range of food groups and dietary patterns, with emphasis on their contribution to obesity and diet-related NCD outcomes. In general, dietary diversity has shown no evidence of an association with overweight and obesity, diabetes or hypertension. However, there have been multiple SRM looking at healthy and unhealthy dietary patterns, as well as specific food groups such as UPF, SSB, red and processed meat, dairy, and fruits and vegetables in relation to these outcomes.

# Discussion

Published evidence on the nutrition and health economic costs associated with dietary risk factors in LMICs is limited. Most of the studies found were based on one specific modeling approach, the GBD, that focuses its estimates on adults and a group of dietary risk factors that are associated with NCD outcomes. While useful for describing the high costs of diet-related NCDs to human life and the health care system, this body of literature has limited relevance for countries facing the DBM, where the burden of undernutrition is still a public health concern, especially in young children. The one study that captured both ends of the spectrum was the Cost of Not Breastfeeding model which described the global costs of child deaths due to infection, child obesity and women’s cancer and T2DM (Walters, Phan, and Mathisen 2019). The estimations nevertheless omit the unpaid health care costs of not breastfeeding, such as lost paid work hours or reduced leisure associated with caring for a sick child, opportunity costs which are largely borne by mothers and contribute to gender inequalities (Smith 2019). NonGBD studies commonly estimated the direct and indirect health care costs for the burden of disease associated with dietary risk factors, evidence that is valuable for increasing awareness of decision makers in LMICs of the burden of disease attributable to diets (Alcaraz et al. 2021).

Similarly, our review of the literature available on the risk of malnutrition associated with diets has revealed the challenges in summarizing a very broad body of research that is not yet well-standardized in terms of common metrics for diet quality. Diet metrics were either limited to the dietary diversity score or they were concentrated on specific dietary factors with known risks for nutrition and health outcomes. Definitions of ‘healthy’ or ‘unhealthy’ dietary patterns varied widely across studies and were often data-driven (derived from analytic approaches such as factor analysis) and context-dependent. The lack of consensus on the use of standardized metrics and the heterogenous dietary measures and outcomes used in quantitative studies are an important impediment for a more precise understanding of the dietary effects on different forms of malnutrition.

Restricting our review to articles with systematic reviews that estimated effect size through meta-analysis was a pragmatic way to consolidate the large body of evidence on associations between diet quality and nutrition/health outcomes; however, this approach resulted in some limitations. Most meta-analyses included a limited number of studies conducted in LMICs and these were more often middle-income countries such as Brazil, China and the Islamic Republic of Iran. The small number of meta-analyses that were focused on low-income countries mostly 12