Is a flexitarian diet enough, or should I go vegan?

The objection

“Surely the realistic answer is everyone cutting back. A few people going fully vegan won’t change much, and even the scientists’ diet for a sustainable planet has some meat in it.”

The answer

Cutting back does real good. Someone who halves their meat spares real animals and real emissions, ten thousand people doing that can outweigh a hundred who go vegan, and anyone who sneers at flexitarians is being unkind as well as tactically foolish. The weak point in the objection is the word “than”, which treats eating less as a destination when it is a direction, and where that direction leads depends on why you started.

What is a flexitarian or a reducetarian?

A flexitarian eats a mostly vegetarian diet with occasional meat or fish [1], and a reducetarian, in the words of the Reducetarian Foundation, a US non-profit, is someone committed to eating less meat and dairy and fewer eggs [2]. Flexitarian, a blend of “flexible” and “vegetarian”, entered the Oxford English Dictionary in 2014, and a 2017 review of the research on these diets found studies defining them in different ways, from leaving out red meat alone to eating meat less than once a week (Derbyshire, 2017) [1]. Neither label sets an amount, and the Foundation leaves the motive to each person [2], so how far to go stays an open question.

Is a flexitarian diet enough for the planet?

A flexitarian diet can sit within the EAT-Lancet Commission’s planetary health diet if its meat is genuinely small, though a vegan diet sits within it too and has a smaller footprint still. In 2019 the Commission, 37 scientists from 16 countries, asked whether a population expected to reach 10 billion by 2050 could eat a healthy diet within planetary boundaries, and answered yes, but only if eating habits changed alongside better food production and less food waste [3]. EAT, the foundation behind the Commission, counts vegetarian and vegan diets as “two healthy options” within that diet, though it calls them personal choices [3]. The Commission’s 2025 update puts beef, pork or lamb at about 15g a day, roughly one portion a week, and chicken or other poultry at 30g, about two servings a week, in a diet of roughly 2,400 calories [4]. The Commission says the diet rests entirely on the evidence about health, and that adopting it would reduce the environmental impact of most current diets [4]. So the meat in the scientists’ diet is the amount the health evidence allows, and each of those ranges runs from zero to double the central amount [4].

At those central amounts, the diet’s 45g of red meat and poultry a day would fall in the lowest meat band of a 2023 Oxford study that matched the recorded diets of 55,504 adults in the UK to a database of 570 life-cycle assessments covering more than 38,000 farms in 119 countries (Scarborough and colleagues, 2023) [5]. With each diet scaled to 2,000 calories and adjusted for age and sex, people eating 100g or more of meat a day had food emissions of 10.24kg of CO2-equivalent a day, those eating under 50g (28g on average) 5.37kg, and vegans 2.47kg, about a quarter as much (the paper’s own estimate puts vegans’ emissions at 25.1% of high meat-eaters’) [5]. Low meat-eaters’ diets had roughly half the footprint of high meat-eaters’, and vegans’ roughly half that of low meat-eaters’. The diets were recorded between 1993 and 1999 among volunteers recruited partly through vegetarian magazines and societies, and the authors note that scaling every diet to 2,000 calories may understate the gaps, since meat-eaters tend to eat more [5]. The same paper cites the UK government’s National Diet and Nutrition Survey, which found adults aged 19 to 64 eating 99g of meat a day on average in 2016 to 2019, right at the edge of the high band [5].

Why go further than cutting down?

How far your reason for cutting back carries depends on which reason it was. If it was the climate, each step down still counts: in the Oxford study every environmental measure rose with the amount of animal food people ate, and vegans had the smallest footprint of any group [5]. If it was the animals, the reason applies just as much to the ones you go on eating. A pig’s suffering that justified eating fewer pigs covers the next pig too, and nothing about the animals left on the plate makes that reason stop at 50%. Applied to animals, the logic that took you to “less” has no natural stopping point short of “none, where you reasonably can”, which is close to how the Vegan Society, a UK charity, defines veganism: excluding exploitation of and cruelty to animals “as far as is possible and practicable” [6], a test that has never demanded perfection.