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.