The world already grows enough food for everyone. That is not a hopeful guess, it is roughly what the numbers say. The problem is that a large share of it is eaten by animals rather than people, another large share is thrown away, and what is left is not shared out evenly. Sustainability in food is mostly about fixing those three losses.
📘 What you need to know
Humans are omnivores, eating fungi, plants, meat and fish.
Diets containing more food from lower trophic levels, such as plant-based diets, are generally more sustainable because of their reduced environmental impact.
Yield of food per unit of land area is significantly higher for crops than for livestock, and crop production has lower financial costs.
Plant-based diets are more energy efficient because of trophic levels, feed conversion efficiency and land use efficiency.
Global agriculture currently produces enough food for approximately eight billion people, but food is not distributed equitably.
At least one-third of all food produced is wasted, at post-harvest, storage, and transport and distribution stages.
SDG 12 aims to ensure sustainable consumption and production patterns; target 12.3 aims to halve global food waste per capita at retail and consumer levels by 2030.
Strategies fall into three groups: reduce demand and waste, reduce greenhouse gas emissions, and raise productivity without expanding farmland.
Eating lower down the food chain
Humans are omnivores, so we have a choice about which trophic level we take our food from. That choice has a large effect on how much land, water and energy our diet needs.
Crops against livestock
Measure
Crops
Livestock
Yield per unit of land area
Significantly higher
Much lower for the same area
Land and resources needed
Less land per unit of food
Requires more land and more resources
Financial cost
Lower costs associated with production
Usually more expensive
Livestock are not wasteful animals. They are simply an extra trophic level, and every trophic level loses most of the energy that enters it to respiration and to inedible body parts.
Three reasons plant-based diets are more efficient
Reason
The mechanism
Trophic levels
Energy is lost at each trophic level as it moves up the food chain. Eating plants directly bypasses the energy loss involved in raising animals, so we use the energy captured by primary producers more efficiently
Feed conversion efficiency
Animals raised for meat need significant amounts of feed, but a large portion of that energy goes into the animals’ own bodily functions and metabolic processes rather than into edible biomass. This inefficiency means higher energy losses when we get nutrition from meat
Land use efficiency
Producing meat needs vast amounts of land for grazing or for growing animal feed crops. That land could grow plant-based food for people directly, so eating plants optimises land use and reduces the energy needed for livestock farming
Put together, focusing on lower-trophic-level food production makes it possible to maximise food production per unit area while reducing the pressure on land resources.
Be careful not to overstate this. Some land genuinely cannot grow crops — the steep, thin-soiled ground from the first page of this topic — and grazing animals there converts grass that people cannot eat into food that they can. The strong version of the argument is about land that could grow crops being used for feed instead. Make that distinction and your evaluation will stand out.
Enough food, badly shared
Global agriculture currently produces enough food to feed approximately eight billion people, and the global population stood at about 8.1 billion in 2024.
Despite this, food is not distributed equitably around the world. Some regions experience surpluses while others face severe shortages.
It is estimated that at least one-third of all food produced is wasted, during post-harvest, storage, and transport and distribution.
This is why waste reduction is such a powerful strategy. Every tonne saved is a tonne that did not need land, water, fertiliser or fuel to replace it.
The SDG detail worth quoting. The United Nations’ Sustainable Development Goal 12 aims to ensure sustainable consumption and production patterns. Within it, target 12.3 focuses on reducing global food waste by 50% per capita at retail and consumer levels by 2030, and on minimising food losses throughout production and supply chains, including post-harvest losses.
Strategies for a sustainable food supply
1. Reducing demand and food waste
Encouraging plant-based diets — shifting towards plant-based diets reduces demand for resource-intensive animal products.
Improving food distribution systems — more efficient distribution helps food reach those in need and cuts waste. Examples include refrigerated transport to keep food fresh for longer, optimising delivery routes to reduce transport time, and collecting and redistributing surplus food.
Educating consumers — raising awareness of food waste at the consumer level can have a significant impact.
2. Reducing greenhouse gas emissions
Plant-based meat substitutes — products that mimic the taste and texture of meat but are made from plants, reducing emissions associated with livestock.
Low methane rice cultivation — practices that produce less methane, such as periodically draining and re-flooding rice fields, and applying additives that reduce methane emissions.
Reducing methane release by ruminants — adjusting livestock diets and using dietary additives such as seaweed to lower methane emissions.
3. Increasing productivity without expanding farmland
Extending shelf life — better preservation, packaging and refrigeration reduce waste along the chain.
Genetic modification — creating crops with higher yields from the same inputs, or crops more resistant to pests and diseases.
In-field solar-powered fertiliser production — using solar energy to produce fertiliser on site, which reduces the need for synthetic fertilisers, cuts reliance on the fossil fuels their production requires, and lowers production and transport costs.
Look at what the third group has in common. Every one of those strategies gets more food out of land we are already using, rather than clearing more. Since land is finite and about 70% of ice-free land is already in use, that is the only direction with much room left in it.
Worked examples
WE 1
Explain the efficiency of plant-based diets
Explain why a plant-based diet is more energy efficient than a meat-based diet. (4 marks)
Point 1: trophic levels
Energy is lost at each trophic level as it moves up a food chain, mainly through respiration.
Point 2: bypassing a level
Eating crops directly means there is no intermediate trophic level, so we avoid one set of losses.
Point 3: feed conversion
Much of the energy in animal feed goes into the animals’ own bodily functions and metabolic processes rather than into edible biomass.
Point 4: land
Meat production needs vast areas for grazing or feed crops, land that could feed more people directly if used for crops.
Fewer trophic levels means more of the original energy reaches humansname all three mechanisms — trophic loss, feed conversion, land use — they are separate marks
WE 2
Explain the food distribution paradox
Global agriculture produces enough food for the world’s population, yet many people are undernourished. Explain this. (3 marks)
Point 1: the supply is sufficient
Enough food is produced globally for approximately eight billion people, close to the current population.
Point 2: distribution
Food is not distributed equitably: some regions have surpluses while others face severe shortages, because of poverty, infrastructure and politics rather than total supply.
Point 3: waste
At least one-third of food produced is wasted post-harvest, in storage, and in transport and distribution, so much of it never reaches anyone.
The shortage is one of access and waste, not of productionsay explicitly that this is a distribution problem — it is usually the central mark
WE 3
Evaluate a strategy for sustainable food supply
Evaluate the use of genetic modification as a strategy for increasing food production sustainably. (4 marks)
Strength 1
GM crops can produce higher yields from the same inputs, so more food is produced without expanding agricultural land.
Strength 2
Greater resistance to pests and diseases can reduce pesticide use and reduce losses before harvest.
Limitation 1
It does not address the underlying problems of unequal distribution and food waste, which cause much of current hunger.
Limitation 2
Like the green revolution, benefits may go to farmers who can afford the technology, increasing inequality, and widespread use of a single variety reduces crop diversity.
Useful for raising output on existing land, but not a solution to access or wastethe green revolution comparison is a strong evaluative move — it shows you can link across the topic
💡 Exam tips
Quote the numbers: enough food for about 8 billion, population about 8.1 billion in 2024, at least one-third wasted.
Know SDG 12 and target 12.3 — halving food waste per capita by 2030.
Use the three named mechanisms for diet efficiency rather than just saying “energy is lost”.
Group strategies into demand and waste, emissions, and productivity without new land.
Say per unit of land area when comparing crop and livestock yields. The unit matters.
Acknowledge that some marginal land can only support grazing — it shows balanced thinking.
⚠ Common mistakes
Saying the world does not produce enough food. It produces roughly enough; the failure is in distribution and waste.
Saying energy is destroyed between trophic levels. It is lost from the food chain as heat through respiration, not destroyed.
Claiming all livestock farming is wasteful. Grazing land that cannot grow crops still converts inedible plants into food.
Treating food waste as only a consumer problem. Large losses happen post-harvest, in storage and in transport.
Confusing SDG 12 with a food-production goal. It is about sustainable consumption and production patterns.
Offering only one strategy in an evaluate question. You need strengths and limitations.
Up next: Food Security and Access — what food security actually means, the four pillars it stands on, and why two countries with the same food supply can have very different outcomes.
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