FAO is focusing its attention on the pursuit of healthy diets and transformations of agrifood systems to ensure healthy diets are affordable for all. Measuring and systematically monitoring the cost and affordability of healthy diets and making progress towards ensuring the affordability of healthy diets is of upmost importance and is urgently needed. To this end, FAO is committed to institutionalize the computation of the least-cost healthy diet, and the corresponding affordability indicator, and to publish updated estimates in the annual The State of Food Security and Nutrition in the World report, as well as provide the full data series on FAOSTAT. This background paper to The State of Food Security and Nutrition in the World 2022 report presents the new methodological refinements applied in the estimation of the average cost of a healthy diet. This is an important methodological update as it results in a more robust indicator that provides greater transparency and supports long-term systematic monitoring utilizing annually updated price data. The paper then explores potential mechanisms and data sources for monitoring globally the cost of a healthy diet.

Cost and affordability of healthy diet (CoAHD) metrics developed in a handful of academic studies have quickly become mainstream food security indicators among major development institutions. The World Bank and FAO now report CoAHD statistics in their widely used databanks, and the UN’s State of Food Insecurity and Nutrition in the World (SOFI) reports CoAHD metrics on an annual basis, with the headline conclusion being that over 3 billion people worldwide cannot afford a healthy diet. While quantifying affordability constraints is indeed a vital addition to the suite of global food security indicators, there is a dearth of scientific analysis on the accuracy and sensitivity of CoAHD methods. Published global CoAHD estimates rely on three implicit assumptions: that demographic differences across countries have little effect on average diet costs; that non-food expenditure requirements have little systematic variation across countries; and that international food price data is representative in a population sense and product coverage sense. Testing these assumptions on the cost of the EAT-Lancet reference diet, we find sizable sensitivity of baseline methods to adjusting diet affordability estimates for systematic cross-country differences in demographic profiles and non-food expenditure requirements, smaller effects of adjusting for inadequate food product coverage in international price data, and inconclusive evidence on issues of urban bias in price surveys. Our proposed methodological improvements significantly change country, regional and global estimates of healthy diet affordability, though not the headline conclusion that several billion people cannot afford a healthy diet. Even so, the accuracy, rigor, and reliability of CoAHD statistics warrant closer investigation given their widespread adoption and utilization.

Price and affordability are key barriers to accessing sufficient, safe, nutritious food to meet dietary needs and food preferences for an active and healthy life. In this study, the least-cost items available in local markets are identified to estimate the cost of three diet types: energy sufficient, nutrient adequate, and healthy (meeting food-based dietary guidelines). For price and availability the World Bank’s International Comparison Program (ICP) dataset is used, which provides food prices in local currency units (LCU) for 680 foods and non-alcoholic beverages in 170 countries in 2017. In addition, country case studies are developed with national food price datasets in United Republic of Tanzania, Malawi, Ethiopia, Ghana and Myanmar. The findings reveal that healthy diets by any definition are far more expensive than the entire international poverty line of USD 1.90, let alone the upper bound portion of the poverty line that can credibly be reserved for food of USD 1.20. The cost of healthy diets exceeds food expenditures in most countries in the Global South. The findings suggest that nutrition education and behaviour change alone will not substantially improve dietary consumption where nutrient adequate and healthy diets, even in their cheapest form, are unaffordable for the majority of the poor. To make healthy diets cheaper, agricultural policies, research, and development need to shift toward a diversity of nutritious foods.

Monitoring of dietary intake at national and global levels is becoming increasingly important with the changing food systems and diets. Better measurement and monitoring are needed to support governments in establishing policies and programmes to promote healthy diets and assess the effectiveness of these actions. However, there is lack of consensus on the indicators that best capture the properties of healthy diets. Recognizing the need for consensus and action, the Food and Agriculture Organization of the United Nations (FAO), the United Nations Children’s Fund (UNICEF), and the World Health Organization (WHO), have joined forces to chart a way forward via Healthy Diets Monitoring Initiative (HDMI). This is the first version of the guidance for monitoring healthy diets globally, which provides an overview of healthy diets measurement purposes, types of surveys suitable for the monitoring purpose, appropriate dietary assessment methods, relevant dietary data types and potential healthy diet metrics for national and global monitoring purposes. The guidance will be enhanced in the coming years to reflect the most up to date technical and operational recommendations, after rounds of consultations with countries and experts actively engaged in the implementation of surveys and data collection processes.

It is vital for countries to monitor their population’s diets to inform actions toward improving the health of people and the planet. The healthiness of diets must be tracked in global frameworks, such as the Sustainable Development Goals (SDGs), to help monitor how the world’s population is faring. Currently, few countries regularly assess diets and there are no dietary indicators in global monitoring frameworks. Recognizing the importance of diets for health and the lack of consensus on how to measure and monitor healthy diets at scale, FAO, UNICEF and WHO joined forces to chart a way forward via the Healthy Diets Monitoring Initiative (HDMI). The joint mission of the HDMI is to enable national and global decision-makers and stakeholders to monitor and achieve healthy diets for people and the planet. The current guidance document is focused on healthy diets for healthy people. This version of the document provides an overview of the range of purposes for measuring the healthiness of diets and offers examples of the dietary assessment methods and types of dietary intake data, surveys and metrics that are currently available to monitor healthy diets.

Aim Cost is a major determinant of food purchases. The central question for this PhD is whether healthy eating costs more than less healthy eating. Monitoring the cost of foods, meals and diets is important to provide evidence to inform policies. Each approach needs standardised methodologies to ensure fair comparisons over time, and between countries. Method Standardised methods were developed and piloted to measure the relative costs of healthier and less healthy foods, meals and diets using commonly consumed foods and locally collected prices. The use of different data sources and methodological approaches was explored to assess the impact on cost. Results The foods approach measured the price of foods over time using the WHO Europe nutrient profile model and the NOVA classification (degree of processing), and compared the cost of pairs of healthier and less healthy foods. The meals approach compared the cost of popular takeaway meals with healthier home-cooked meals, incorporating the cost of preparation or waiting time. The diet approach compared the cost of a healthy and a current diet. Healthier and less healthy foods, and minimally processed, processed and ultra-processed foods all increased in price at a similar rate over ten years. The healthier items of a pair tended to cost the same as, or more than, the less healthy counterpart. Healthier home-made and home-assembled meals were less expensive than their takeaway counterparts. When time was included, home-assembled meals were the cheapest option and half the home-made meals were at least as expensive as the takeaway meals. The healthy and current diets were similar in price when only the current diet contained alcohol and takeaways, and the energy requirement of the diets was to maintain the recommended BMI for an active person (healthy diet) or maintain the current BMI at current activity levels. Altering aspects of diet, including or excluding takeaways, and generic labels, and altering the energy requirements had considerable impacts on cost. Conclusion This thesis developed novel methods to provide a simple, standardised approach to monitor the price of healthier and less healthy foods, meals and diets enabling comparisons over time, and between countries.