Vegan, Vegetarian or Meat-Eater: What 55,000 UK Diets Reveal About Emissions

The study

Researchers led by Peter Scarborough at the University of Oxford took dietary records from 55,504 adults in the UK and grouped them into six categories: vegans, vegetarians, fish-eaters, and low, medium and high meat-eaters (high meant 100 g or more of meat a day). They linked each reported food to environmental data drawn from a review of 570 life-cycle assessments covering more than 38,000 farms in 119 countries.

That global farm dataset matters. The same food can have very different footprints depending on where and how it is produced, so instead of using one fixed number per food, the researchers modelled that variation and reported uncertainty ranges alongside their central estimates. It is the same underlying farm review (Poore & Nemecek, 2018) that many food carbon calculators, including Decarbonr’s food factors, draw on.

It is a gradient, not a switch

The headline comparison — vegans at roughly a quarter of the emissions of high meat-eaters — gets most of the attention. The more useful finding for most people is the shape of the curve. Emissions did not jump only when meat disappeared entirely; they rose steadily with the amount of animal-based food in the diet. Low meat-eaters already had substantially lower impacts than high meat-eaters on most measures.

That reframes the choice. You do not have to adopt a label to see a meaningful difference. Moving from a high-meat pattern towards a lower-meat one is itself a large step, and every portion of beef or lamb replaced with a plant-based or lower-impact alternative moves your number in the same direction.

Where the study is less certain

Independent experts who commented on the paper raised fair points. The uncertainty ranges for the middle groups — vegetarians, fish-eaters, and low and medium meat-eaters — overlap considerably, so the study separates the extremes more confidently than it ranks the groups in between. Applying farm-level assessments from many countries to UK diets also adds uncertainty, as does the fact that the analysis worked at the level of primary ingredients rather than the processed foods people often buy.

The diet records were self-reported, and the participants were volunteers rather than a representative sample of the UK population. None of these caveats overturns the main pattern, which the authors describe as clear despite the variation in how food is produced, but they are good reasons to treat any single percentage as an estimate rather than a precise figure.

What this means for your own footprint

The practical lesson is that the amount of animal-based food matters as much as the category you put yourself in. Two people who both call themselves meat-eaters can have very different food footprints, and the difference shows up meal by meal rather than once a year.

That is also why seeing your own pattern helps. A general comparison tells you that diets differ; logging what you actually eat over a few weeks tells you which meals carry most of your food emissions and which swaps would change your number the most. For many people it is a small number of high-impact meals, not the whole diet, that does most of the work.

Diet choices also involve health, cost, culture and access, which this study did not set out to weigh. It answers one question well — how the environmental footprint of real UK diets scales with animal-based food — and leaves the rest of the decision to you.