[Home](/)

Why food

The question underneath the directory

# Why this site looks at any of this

Agriculture uses more of the planet's land than anything else people do, and most of that land grows food for animals rather than for people. Stop routing the food through an animal first and the same land can feed us, power a civilisation and go back to nature. Here is the arithmetic, where it is uncertain, and what each kind of new food removes.

Sources checked 21 September 2026 · an argument, not advice

This page is the site's own case, argued in its own voice over dated sources. [What we know](/what-we-know/) is the other kind of page: one fixed question at a time, and every factual sentence there has passed a gate that this argument's prose does not claim.

## The short version

Agriculture uses more of the planet's land than anything else people do. Most of that land is used to raise animals or to grow food for them. In return, animal products supply a minority of the calories and protein people eat.

The gap between those two facts is a conversion loss, and it is large. Measured per unit of food, beef and lamb need roughly fifty to ninety times more land than the plant foods that would replace them. Beef also needs six to twenty times more water than most plant staples, and several times more feed than the animals that convert feed best.

That is the whole reason this site exists. Not because new foods are novel. Because each one is an attempt to remove a step from a chain where the step is most of the cost.

## Why the step costs so much

A plant turns sunlight into food. A person can eat the plant, and that is one step. Or the plant can be fed to an animal, which spends most of it staying alive, and the person eats what is left. That is three steps, and every one of them keeps some of what passes through it.

And the step before it costs more still. Feeding the animal is the second loss in the chain. The first is that the plant itself keeps almost none of the light that falls on it. The photosynthetic efficiency of most crops is "generally below 1% and often closer to 0.25–0.5%", measured as the conversion of incident solar energy into energy in available excess biomass (Taylor et al., APS PRX Energy 4:017001, 2025, whose denominator this is). Ort et al. put season-long conversion for crop plants at "typically do not exceed a few percent" (PNAS 112:8529, 2015). A 2026 review by Zhou et al. (J. Integr. Plant Biol. 68:2608) puts the actual efficiency of modern crop canopies at about 2.2% for C3 crops and 3.0% for C4. So the loss is not something the animal introduces. It is already there in the field, and the animal multiplies it.

Why the plant keeps so little, and why it is not a fault. The enzyme that fixes carbon, Rubisco, is slow — it handles only a few CO₂ molecules per second, against fifty to a hundred for comparable enzymes — and it does not reliably tell CO₂ from O₂. When it grabs the wrong one the plant has to run photorespiration, which costs it energy and gives back some of the carbon it had already fixed: 20 to 50% of the efficiency with which C3 crops turn light into biomass, with the largest losses in hot, dry places. It is also expensive to build, at 30–50% of the soluble protein in a leaf. But the honest reading is not that Rubisco is a bad enzyme. The literature's own conclusion is that it is near-optimised for the compromise it faces, trading accuracy against speed as well as any enzyme could. And it is not the whole explanation. No source we could retrieve splits the loss between Rubisco and the light a leaf simply cannot use — absorbing more photons than it can process is a large part of the same inefficiency. So this page says the loss has several causes and Rubisco is one of them, not that photosynthesis is 1% because of Rubisco.

The loss is measurable. Of the food energy an animal eats, this is what comes back as food:

Two steps, two measurements, and this page does not multiply them. The first figure is about sunlight turned into biomass; the second is about feed energy turned into food. No source we could retrieve measures sunlight in to food energy out, so the chain above is two losses that both happen rather than a single number, and we do not present a combined one.

### What comes back as food, per unit of feed energy

Beef 1.9%, lamb 4.4%, pork 8.6%, poultry 13%, eggs 19%, whole milk 24%. Global figures for 2013; Alexander et al. (2016), retrieved as Our World in Data's published dataset. Sorted from highest to lowest. Beef is the hardest case in the table. Feed a beef animal a hundred calories and under two come back as beef. Milk returns twelve times what beef does, which is why "livestock" is never one number and why this page reports ranges rather than a slogan.

The animal is not being wasteful. It is a living thing, and staying alive is what most of the energy goes on. The same is true of us.

## Where the numbers are big, and where they are not

The factor is not one number, and this is the part a reader should test us on. It depends on the animal, on how it was raised, on whether we are counting calories, protein or land, and on whether grass and crop residues count as feed. Those are real choices, and different studies make them differently.

Land is where the gap is widest. Water and feed are narrower. And on one measure the gap closes entirely.

### Land needed per 100 g of protein

Square metres of land for one year, per 100 g of protein. Tofu 2.2, wheat and rye 3.2, peas 3.4, grains 4.6, eggs 5.7, poultry 7.1, other pulses 7.3, nuts 7.9, pig meat 11, dairy-herd beef 22, milk 27, cheese 40, beef-herd beef 164, lamb and mutton 185. Global means, from studies whose median year is 2010; Poore & Nemecek (2018), retrieved as Our World in Data's published dataset. Sorted from highest to lowest. On land per unit of protein, beef from a beef herd needs about seventy-four times the area of tofu, and lamb about eighty-four times.

On water, beef is the outlier at roughly twenty times cereals and starchy roots per calorie, and six times pulses per gram of protein. Milk, eggs and chicken are only about one and a half times pulses per gram of protein, so the factor nearly disappears for those three.

On feed, whole-cycle conversion in US systems is about 14.97 pounds of feed dry matter per pound of liveweight for beef cattle, against 2.19 for broilers. A Canadian benchmark for the feedlot stage alone is 6.35 kilograms of dry matter per kilogram of gain. The two figures differ because the feedlot figure leaves out the grass a beef animal eats for most of its life, and the calf and backgrounding phases before the feedlot.

And here is the measure that runs the other way. Counting only food that people could have eaten themselves, ruminant systems use 2.8 kilograms of human-edible feed per kilogram of boneless meat, against 3.2 for pigs and poultry. On grazing and forages, the authors of that feed study (Mottet et al., 2017) say in their own summary that cattle need only 0.6 kilograms of protein from human food to produce a kilogram of protein in milk and meat. On that accounting, some cattle add to the food supply rather than subtracting from it, and about 86% of the six billion tonnes of feed that livestock eat each year is material people do not eat.

We publish that because a page that hides it is a page that can be taken apart by the first person who knows it. The argument here is about land, water and calories. It is not a claim that animals are a bad way to make food. It is a claim about what the conversion step costs, and the cost depends on which currency you count in.

## The land is the part that matters most

Land is the constraint that decides everything else, because land is what habitat, carbon and energy all need.

The world has about 4.8 billion hectares of agricultural land. That is more than a third of all land and almost half of the land that is not ice or desert. Of that, about 1.6 billion hectares is cropland and about 3.2 billion hectares is permanent pasture.

Combine the pasture with the cropland used to grow animal feed and livestock accounts for about 80% of agricultural land. Crops grown for people account for about 16%. Non-food crops, mostly fuel and fibre, take about 4%.

For that 80%, animal products return roughly 17 to 18% of the world's calories and 36 to 40% of its protein, depending on whether seafood is counted. Different sources give different pairs for that second figure, so we have given the range rather than choosing the flattering end.

One more thing belongs here, because it limits what "freed land" can mean. The authors' own summary of Mottet et al. (2017) says that most of the land used to feed livestock is grassland, with a large share of pastures that could not be converted to cropland and could only be grazed. Pasture is not cropland waiting to happen.

## What a better farm does not fix

Yields have risen for decades, and feed conversion has improved. Total impact is area multiplied by impact per hectare, and gains per hectare tend to be spent on producing more rather than on farming less. The systems literature calls this a rebound effect.

So the useful question is not how to make one conversion step cheaper. It is how many conversion steps we need. That reframing is what turns a problem into a map of possible answers, and it is the reason the categories on this site are worth separating: each one removes a different layer.

## What the land could do instead

If the world ate plants directly, research based on the largest food life-cycle dataset estimates that agricultural land use would fall from about 4.1 billion hectares to about 1 billion. That is a reduction of roughly 75%, an area the size of North America and Brazil together. Cutting out beef, mutton and dairy does most of the work, and large reductions are possible without anyone becoming vegan.

That land is the prize, and it has three bidders: food, energy, and nature.

Energy is the one people find surprising. Counting only the land a solar farm itself covers, solar power occupies between 0.03 and 1.5 hectares per gigawatt-hour depending on the study, against 37.5 to 81 for bioenergy crops, and the best measured figure, from US solar farms, is about 0.9 to 1.0. Put today's entire global primary energy supply on solar at that measured figure and it takes about 1.5 million square kilometres, roughly five percent of the land that would be freed, and about 9 to 10% of the world's cropland. On the measured footprint, land is not what limits the energy transition. The size of the build is: primary energy is nearly six times today's electricity. Primary energy overstates what an electric system would need, so treat these areas as upper figures.

Nature is the other bidder, and the strongest one. Restoring land to forest takes up carbon at roughly five to ten tonnes of CO₂ per hectare per year over about a century, with a range of one to twenty, and the IPCC warns that the potential may be overestimated. But this is not a simple promise. The IPCC is clear that land-based carbon removal does not store carbon forever, and that planting trees on native grassland destroys the ecosystem it is meant to compensate for.

So the three claims compete for the same hectares. On the measured footprint, a tenfold expansion of energy on freed land would take about half of it. If all of that land would otherwise have been restored, it would give up several billion tonnes of CO₂ a year that restoration would have taken up instead. Freed land is not free land, and this page will not pretend otherwise. What is true is that today agriculture holds the hectares and the other two go without. Removing the conversion step is what makes all three affordable at once.

## Where we are least sure

This section is where the argument is weakest, and it belongs on the page rather than in a footnote.

Where the land is. The arithmetic above uses global averages, and averages are not places. Most of the land that would be freed is pasture, much of it at high latitudes and far from cities and power lines. On the regional intensities that apply where land actually is, a tenfold energy expansion would need from more than three to sixteen times all the land that would be freed, not half of it. Those regional figures come from India and the EU, and the source warns that they hold region by region and must not be applied to the whole world. They also measure something different from the global average: the land a region must take out of crops or forestry, including land displaced elsewhere, not only the land the panels cover. Capacity factors inside a single country, the United States, range from 11.5% to 29.8%. No source we found says what share of freed pasture could realistically carry solar, so the claim here is about the size of the pool, not about what could be built.

What the land is worth. Restoring a hectare is not a fixed quantity of carbon, and no source we found puts a reliable number on the biodiversity value of a hectare. We have published the range rather than a headline.

Things we looked for and could not get. The Haber-Bosch figure that about half the world's population is fed by synthetic nitrogen, which is widely quoted and whose primary source refused us. Whether agriculture exceeds the planetary nitrogen boundary, which depends on which boundary you use, and where the answer we could source, a 2020 report from the Potsdam Institute for Climate Impact Research and the Stockholm Resilience Centre, puts it at roughly 78% of the application boundary, under rather than over. The land footprint of storage and transmission for a solar grid. And any published land or water footprint for fermentation-derived or cultivated protein, which is the gap the comparison page names explicitly. And the ceiling on photosynthesis, which is the number a reader will ask for next: the literature carries more than one theoretical maximum, each on a different basis, and no source we retrieved states how they relate. They are not the same measurement, so this page publishes the range it can check and no ceiling at all.

## What each kind of new food actually removes

This is the part that turns the argument into a map. Every category on this site is an attempt to delete a named layer from the chain, and it is worth being precise about which layer, because it says what each one can and cannot fix.

Some of these will not work at scale. Some are already working. What they have in common is that none of them is a novelty for its own sake: each is aimed at a specific cost in the chain above, and that is the test to hold them to.

### Plant proteins

RemovesThe animal — Pulses, tofu, tempeh, seitan and whole cuts. The plant goes to the person directly, so there is no conversion step to pay for. This is the only route that removes the whole step, and the only one already at scale.

### Traditional fermentation

RemovesNothing — it improves what is already food — Tempeh, miso, koji. Familiar ingredients, fermented. The lowest-risk route and the oldest, and it does not claim to replace anything.

### Mycoprotein and biomass

RemovesThe animal as an organism — A fungus or a microbe grows protein from feedstock without an animal's metabolism in the middle, and without a farm animal's land.

### Precision fermentation

RemovesThe animal as a factory — A microbe makes one specific molecule — a protein, a fat, an enzyme — that would otherwise need a cow, a hen or a field.

### Cultivated meat and seafood

RemovesThe animal's body, feed and land — Cells are grown into tissue, so the conversion happens at the cell rather than through a whole organism's lifetime.

### Novel inputs — sweeteners, fats, side streams, gas

RemovesA specific input — Sugar from a sweet protein rather than a cane field; fat from a fermentation rather than a palm plantation; protein from a side stream or from CO₂ rather than from a new field.

## What this page does not show

This is an argument built from published sources, written by this site. It is not a review, and it is not advice.

It does not show that any food on this site is better for you. We make no health claim anywhere on this page.

It does not show that any food on this site has a lower environmental impact than any other. The figures here are for food categories and global averages, not for the products we list.

It does not show what any particular farm, maker or product does. A single food's footprint varies widely depending on how and where it was produced.

It does not show that eating differently would change the world on its own. It shows what the land is currently doing, and what the arithmetic of changing it looks like.

It does not establish that fermentation-made or cultivated protein has a low impact. No comparable published figure exists, which is a gap rather than a result.

It does not show that livestock are wasteful. On human-edible protein, some grazing systems return more than they take, and this page says so.

It does not settle what should happen to land that stops being farmed. Three uses compete for it, and choosing between them is a public decision, not ours.

It does not measure the effect of this page on anyone's behaviour. That is unobserved.

It does not cover water quality, soil health, farm income, rural employment or animal welfare. Each is a real part of this subject and none is settled here.

It does not show that the food on this site is available where you live. Availability is checked separately, listing by listing, and dated.

It does not rely on any figure we could not retrieve and read. Where a widely quoted number failed that test, the page says so instead of using it.

— no named reviewer has reviewed this page, and no clinician has. It is a compilation of published sources by this site.

## Our position

Written by Find My Next Bite · 20 September 2026

The conversion loss is real, it is large, and it is the only environmental argument this site needs. It is also not a moral claim about anyone's dinner. A tax is not a sin, and the animal is not the villain: it is a metabolising organism doing exactly what evolution built it to do, and on some pasture, in some systems, it is the best available way to turn land into food.

What we think follows from the arithmetic is narrower and, we hope, harder to argue with. Land is the binding constraint on habitat, on carbon and on energy at once, agriculture holds more of it than any other human use, and most of that land exists to support a conversion step that loses most of what passes through it. Any step we can skip is a step we no longer pay for.

## The last word

Nothing here asks you to give anything up. The interesting question is not whether these new foods are perfect — it is how much of the wasted step each one removes, and what the freed land could then do. And this page gives no health advice.

## How this page was made

Every figure here comes from a source we retrieved and read, and each one is dated. Where two sources disagree we publish the range rather than picking one. Where a widely quoted number could not be traced to a source we could read, we say so on the page and leave it out.

The sources behind this page are listed below with the date we checked them. They are agriculture and land statistics from the UN Food and Agriculture Organization, the IPCC's reports on land and on climate mitigation, and peer-reviewed work on food life-cycle impacts, water footprints, feed conversion and nitrogen. Where a figure comes from a dataset a publisher has released rather than from the paper itself, the page says which.

Figures for how much land a food needs are global means, and individual producers vary widely around them.

Water figures are global averages for the period 1996–2005, from the standard reference on the subject.

Energy conversion figures are for 2013 and come from a published dataset accompanying a peer-reviewed review.

The energy comparison uses today's global primary energy and current solar land intensities. It is arithmetic from sourced figures, and the assumptions are stated on the comparison page.

## Where to go next

The argument is only useful if it leads somewhere you can act on.

[See how the foods compare →](/why/compare/)[Browse the plant-based foods →](/foods/?category=plant-based)[See everything in the directory →](/foods/)

This page makes no claim about any named product, carries no promotion, and no listing on this site pays for its place in these charts.

## Sources, and when we checked them

[FAO, Land statistics (FAOSTAT Analytical Brief), data year 2018](https://openknowledge.fao.org/server/api/core/bitstreams/a46b2504-770c-43a8-a63a-6ae5fcd71e63/content) — 4.8 billion ha agricultural land; 1.6 cropland; 3.2 pasture. Checked 19 September 2026.

[IPCC, Climate Change and Land — Headline Statements, 2019](https://www.ipcc.ch/site/assets/uploads/2019/11/Headline-statements_Final.pdf) — AFOLU, 2007–2016: 81% of anthropogenic N₂O, 44% of methane, 23% of net GHG emissions. Checked 19 September 2026.

[Poore & Nemecek (2018), Science 360:987–992 — retrieved as Our World in Data's published CSV](https://ourworldindata.org/grapher/land-use-protein-poore.csv) — Land per 100 g protein and per 1000 kcal. The Science article itself refused retrieval (HTTP 403); the dataset was read from the publisher's release. Checked 19 September 2026.

[Mekonnen & Hoekstra (2010), The water footprint of farm animals and animal products, UNESCO-IHE](https://waterfootprint.org/media/downloads/Report-48-WaterFootprint-AnimalProducts-Vol1_1.pdf) — Litres per kg by animal; 98% of the footprint is feed, not drinking water. Checked 19 September 2026.

[Mottet et al. (2017), Global Food Security 14:1–8 — abstract](https://doi.org/10.1016/j.gfs.2017.01.001) — 6 billion t feed dry matter, 86% human-inedible; 2.8 kg ruminant against 3.2 kg monogastric human-edible feed per kg boneless meat. Checked 19 September 2026.

[Alexander et al. (2016) — retrieved as Our World in Data's published CSV](https://ourworldindata.org/grapher/energy-efficiency-of-meat-and-dairy-production.csv) — Feed-to-food energy conversion, data year 2013. Checked 19 September 2026.

[Lassaletta et al. (2014), Environmental Research Letters 9:105011](https://doi.org/10.1088/1748-9326/9/10/105011) — About 47% of applied reactive nitrogen reaches the harvested crop. Checked 19 September 2026.

[IPCC AR6 Working Group III, Chapter 7 — Agriculture, Forestry and Other Land Uses](https://www.ipcc.ch/report/ar6/wg3/downloads/report/IPCC_AR6_WGIII_Chapter07.pdf) — 5–10 tCO₂ per hectare per year over about a century, range 1–20, for reforestation and afforestation. That land-based removal does not store carbon indefinitely is from AR6 Working Group I, Chapter 5. Checked 19 September 2026.

[Ritchie, Our World in Data, 4 March 2021 — agricultural land under a plant-based diet](https://ourworldindata.org/land-use-diets) — 4.1 billion ha to 1 billion ha, −75%. Checked 19 September 2026.