Revealed preferences towards and away from healthy diets

Low and lower-middle income countries have declining rates of undernutrition as measured by micronutrient deficiencies or stunting, but a rising burden of other diet-related diseases such as diabetes and hypertension. Using household survey data from Malawi, one of the world’s lowest income countries, we find that the quality of diets rises with income up until incomes of approximately $2.60 international dollars per person per day (2021 PPP), well above the international poverty line ($2.15) but below the average cost of the least-expensive healthy diet available in Malawi ($3.03) (FAO; IFAD; UNICEF; WFP; WHO, 2024b). The wealthiest households consume vegetables, legumes, nuts and seeds below recommended thresholds, and consume more calories from starchy staples and discretionary foods than are needed for health. This results in lower diet quality in terms of risk factors for disease than could be achieved at that level of income. This evidence suggests that rising incomes alone may not sufficient to improve diets in extremely low-income settings over the long term, although income transfers remain imperative to improve diets and well-being of the poorest households. Targeted income increases among households with higher baseline diet quality appears better-suited to producing diet quality increases. Other approaches that target marginalized households or target specific food groups (fruits, vegetables, and legumes, nuts and seeds) may be needed to make significant diet quality improvements among the rest of the population.