Messages around healthy eating are nothing new—but nowadays we are increasingly told to eat well not just for our own health but also for the planet. 

This debate was given a boost at the beginning of 2019 with the publication of the EAT-Lancet Commission report on the world’s diet, which called for a “great food transformation.”

It condemned the world’s “faulty food system” which sees nearly 1 billion people go hungry, almost 2 billion eat too much of the wrong type of food, and which puts unsustainable pressure on the planet.

The report also published the first ever global “reference diet” which outlined what foods we should eat more of and, importantly, what we should consume less of. 

The diet was designed so that it could be adapted to any cuisine anywhere in the world and included tastier—but more expensive foods—such as fruits, nuts, fish and dairy to make it more palatable.

But while this diet—rich in vegetables, grains and complex carbohydrates but low in meat, saturated fat, sugar and salt—is undoubtedly healthy, it is also unaffordable for many people around the world. 

In a new study published in The Lancet Global Health, we estimated the proportion of people across 159 countries for whom the diet was too expensive. Our findings help us to understand the global food system and the true extent of food poverty globally.

Using retail prices from around the world, we measured the local cost of following the EAT-Lancet recommendations and the relationship to household income.

Even after using the cheapest locally available items in each food group and each country, we found that at least 1.58 billion people globally could not possibly afford to follow this diet. 

In rich countries the grocery bill for the cheapest EAT-Lancet diet would be much lower than the current average food budget. This is because the average consumer’s shopping cart would contain more plant-based proteins and much less meat and dairy. 

But people in low income countries who wanted to follow the cheapest EAT-Lancet diet would still end up spending 90% of their daily income on food.

For the world’s poorest consumers food choice is all about affordability. Rather than eating a diverse and nutritious diet, the poor typically eat a near-subsistence diet, formed largely of starchy staples such as rice, maize, or cassava. This satisfies daily energy needs, but falls short of many of the nutrients needed for lifelong health. 

In low income countries we found that the median cost of the EAT-Lancet reference diet was $2.40. This may seem low, but when the World Bank’s international poverty line is $1.90 per day it shows that for many people following a healthy diet is simply too expensive. 

Even though there are no quick-fix solutions for ensuring nutritious food for all, a few things are clear.

First, increasing the real incomes of the poor is vital for improving their diets—without higher incomes the poor simply cannot afford to eat more healthily. 

Second, another important way to raise real incomes is to reduce food prices through smarter investments in food systems, especially for foods that are rich in nutrients but are also expensive.

These items are often produced by poor farmers who could benefit from higher productivity and greater demand. Our study shows that the cost of an EAT-Lancet diet is inflated by relatively high prices for fruits, vegetables and healthy animal-sourced foods like milk, eggs and fish. These are particularly expensive in low-income countries. 

In most of Africa and South Asia, the high cost of a healthy diet stems partly from low productivity on the farm, but also from poor infrastructure and inefficiencies off the farm in storage, transport and processing. 

Third, we know that having lower-cost, healthier ingredients available to buy is only the start of a better diet. As diverse options become more affordable—including unhealthy items like sugary drinks and salty snacks—taste and convenience become the driving force in food choice. 

Governments must address the serious health risks of poor diets not only by educating consumers about these risks, especially school age children and parents, but also by regulating food processing, labelling and marketing. 

Taxes on unhealthy food such as sugar are also vital to make unhealthy options less attractive and provide revenue to fund investments that help us make healthier and more sustainable food choices. 

While overhauling the world’s diet will undoubtedly be a challenge it also offers a high reward: A healthier and more sustainable global food system for the 21st century.

Kalle Hirvonen is a Senior Research Fellow with IFPRI’s Ethiopia Strategy Support Program and Development Strategy and Governance Division, based in Addis Ababa. Derek Headey is a Senior Research Fellow with IFPRI’s Poverty, Health and Nutrition Division. William A. Masters is a Professor and Yan Bai is a doctoral student at the Tufts University Friedman School of Nutrition. This post first appeared in The Telegraph.

This study was funded by the Bill & Melinda Gates Foundation through the project Advancing Research on Nutrition and Agriculture (AReNA).