Transforming food systems: how a flexitarian diet can combat climate change and boost health

Five years ago, a global panel of nutrition and health scientists, the EAT-Lancet Commission on Food, Planet, Health, proposed a “planetary health diet” as the answer to this question: Can we feed a future population of 10 billion people a healthy diet within planetary boundaries?

What they proposed became known as a “flexitarian” diet, a mainly plant-based way of eating that would “optimise human health”, said the scientists, while reducing the environmental impact of food production — especially that of cattle farming and meat production — which is responsible for 70% of freshwater use and 30% of global greenhouse gas emissions, of which the production of animal-based food makes up 15%.

What the planetary health diet made concrete is that if some or most of us 8.2 billion humans begin to eat less meat and other animal products, while increasing our consumption of plants, we could turn the tide on climate change. Our individual choices, which drive demand for certain foods —  and therefore what is farmed, and how — do matter.

The climate- and biodiversity-related facts around agriculture make it plain that industrial agriculture, especially raising cattle and growing maize and soy to feed them, involves destroying natural habitats. Land conversion for food production, says the EAT Forum, is the single most important driver of biodiversity loss.

Read more: South Africa’s beefy impact: the road toward a just transition on climate, cattle, and equity

Then there is the methane that cattle burp into the atmosphere: gases produced by food fermenting in the animals’ guts (technical term: enteric fermentation).

Methane is the same gas that is produced by landfills and food waste and is between 28 and 80 times more potent than carbon dioxide at trapping heat in the atmosphere. Its potency drops after 20 years, which means that reducing methane emissions is a highly effective short- to medium-term lever to reduce the damage caused by greenhouse gases.

Why do we need a ‘planetary health diet’? 

One-third of all greenhouse gas emissions are caused by the global food system, with meat and other animal-based food production making up 57% of that. This is twice that of plant-based foods (29%) and more than the emissions from all forms of transportation combined.

These numbers make it clear that food systems play a huge role in driving climate change, destroying wildlife and polluting seas and waterways. Our food systems are “broken”, said the UN secretary-general in 2023 at the UN Food Systems Summit in Rome. Science underpins that claim, backed by a group of 130 national science academies that published a report, three years in the making, describing the problems and potential evidence-based solutions.

The scientists on the EAT-Lancet Commission have called the planetary health diet a “win-win” because it would prevent 11 million deaths a year caused by illnesses driven by unhealthy foods and would preserve our planet’s ecosystems, on which we all depend for survival.

What does the planetary health diet look like? 

“There is no silver bullet but solving the problem starts with changing what we eat and waste,” say scientists on the EAT Forum website. “By choosing this diet, we can drive demand for the right foods and send clear market signals all the way through the food value chain back to the farmers.” This means “go easy on meat consumption” and eat more fruits, vegetables, nuts, legumes and whole grains.

Marco Springmann of Oxford University, who was part of the commission in 2019, told The Guardian newspaper: “The planetary health diet is based on really hard epidemiological evidence, where researchers followed large cohorts of people for decades. It so happens that if you put all that evidence together you get a diet that looks similar to some of the healthiest diets that exist in the real world.”

Depending on where in the world you live, this could mean making dramatic changes — in North America, for example, you would need to eat one-sixth of the red meat you currently consume and six times the beans and lentils. In South Africa, where our per capita meat consumption (18kg) is much closer to that of a high-income country such as the US (21kg) than a low-income country (4kg), we would need to make similar major changes.

Across the globe, human consumption of red meat, eggs, poultry and dairy far exceeds the levels (shown by the “100%” vertical, red dotted line) recommended by the “planetary health diet”, while consumption of fish, vegetables, fruit, legumes, whole grains and nuts generally falls far short.

Coming soon: Version 2.0 

Though the EAT-Lancet Commission report was published in the world’s most highly esteemed medical journal (The Lancet) and was sent to policymakers in 40 cities around the world, its appearance did not kickstart a huge wave of changes to national food policies.

Four years on, the commission and the report’s authors are working on an updated version, which will feature regional and cultural variations on the planetary health diet.

The head of Norway’s EAT forum (the other partner in the commission), Gunhild Anker Stordalen, in a recent online post titled “There is no such thing as one global diet”, declared: “Dietary shifts are among the most impactful actions we can take to reduce the environmental impact of our food systems, improve human health, and unlock significant economic gains.

“However, to implement these changes effectively, dietary recommendations must be tailored to the cultural heritage, values and preferences of populations.”

Stordalen was drawing attention to a recent editorial in the scientific journal Nature Food, written by the EAT-Lancet report authors Brent Loken, Murli Dhar and Nancy Phoebe Rapand, in which they explained why the commission is working on a Version 2.0.

“Coming up with a viable strategy for achieving dietary shifts in countries around the world is critically important, as dietary shifts may be the single most important action for reducing the environmental impacts from food systems,” they said, “and obviously the most important action for improving human health.”

Despite this, they said, it is hard and slow work to make lasting progress on dietary shifts, as “most countries around the world are far from even achieving their own national dietary guidelines”.

The authors highlighted “one important barrier: the need to find culturally appropriate solutions to the growing global call for a shift to health and sustainable diets”.

The planetary health diet has been widely discussed and debated and has also come under fire, with critics saying it is unaffordable, that it ignores the fact that for many people the recommended foods are unavailable or inaccessible, and perhaps most prominently, that “it lacks appreciation of cultural values, consumer preferences and food dependencies, meaning local variations are required”.

Version 2.0 of the planetary health diet, due in late 2025, aims to address these criticisms. It will still be “a flexitarian diet” — largely plant-based but “can optionally include modest amounts of fish, meat and dairy foods”. It will also include recommendations on regional and culturally relevant permutations, to be known as “regional reference diets”.

One example the authors outline to illustrate this is of communities in Kenya, where diets are diverse, “culture plays a strong role in food preferences”, and the staple food is ugali (a maize, sorghum and cassava version of pap). In the Luhyia community, ugali is usually eaten with local vegetables and very little meat or fish; in central Kenya, a community called Agikuyu eats mainly a mix of grains, cabbage and potato; while the Maasai eat mainly meat. Building on these kinds of cultural preferences, “region-specific reference diets” could be created, improving health and minimising environmental impacts.

EAT Forum’s Stordalen says governments are responsible for ensuring something like a planetary health diet is accessible to their people.

“Governments have a pivotal role in making culturally appropriate diets both affordable and accessible to all,” she says. “Achieving this will require a holistic food systems approach across the entire value chain and bundling of policies. Right now, the food industry often dictates our dietary choices — but it’s time for that to change.” DM