People can eat sustainably and protect their wallets at the same time: in fact a new study that drew on data from almost every country finds that diets which are good for people and the planet are typically some of the cheapest, too.
That challenges assumptions that sustainable diets are by default more expensive, the researchers say.
For the study, they gathered dietary data from 171 countries, calculating the economic costs and greenhouse gas impacts of locally-available foods in each case. The researchers then took a diet of the most commonly-consumed foods in each country, and compared it with other hypothetical diets, made up of from the same array of local foods, but tweaked to focus on lowering greenhouse gas emissions, or reducing costs.
Their modeling showed that consuming diets made up of the most common foods across the globe would generate 2.44 kilograms of CO2-equivalent per person each day, and cost an average $9.96. Compared to that, national diets designed to have the lowest greenhouse gas emissions and still meet nutritional demands in each case would slash daily per capita global emissions to an average 0.67 kgCO2e.
Then, when the researchers tried to balance health with low cost by developing nutritional diets that used the least expensive foods in each country, they found this would cost just $3.68 per person per day on average—three times less than the default diet made of the most consumed foods.
More interestingly, this healthy, economical diet was also more sustainable, generating an average 1.65 kgCO2e per person per day. While that’s higher than diets designed purely to reduce emissions, it’s a third less than the default common food diet—and suggests that sustainable food can be an affordable choice.
This study trades on the fact that there is enough variety within dietary food groups that we are able to swap out pricier, higher-impact foods for lower-impact options that are just as nutritious. As a general rule this means that “choosing less expensive options in each food group is a reliable way to lower the climate footprint of one’s diet,” the researchers say.
There were some interesting exceptions. In many countries dairy milk is the cheapest and most nutritious of animal-sourced foods, and yet it produces substantial emissions. Foods like mackerel and sardines in these countries would have lower emissions per calorie and are a similarly nutritious substitute—but would be slightly pricier, the researchers found.
Likewise, rice is one of the cheapest grains globally, but the way it’s farmed produces large amounts of methane. Wheat and barley, meanwhile, cost a little more but produce much less in the way of greenhouse gas.
But overall, the logic holds: it’s possible to eat on a budget and do your bit for the planet, according to the research: “At the grocery store, frugality is a helpful guide to sustainability.”
Bai et. al. “Environmental impacts and monetary costs of healthy diets worldwide.” Nature Food. 2025.
Image: based on Kovina Đurić/Unsplash.
