Which diet is the most environmentally friendly?

Is going vegan best for the planet?

Yes, essentially. A new study by Oxford University found vegan diets massively reduce our impact on the environment – they lead to 75 per cent less greenhouse gases, water pollution and land use than a meat-eater’s diet. Vegan diets also reduce the destruction of wildlife by 66 per cent and water use by 54 per cent.

But we know going vegan isn’t perfect. Plant-based milks do have lower carbon emissions and use less land than dairy milk, but they’re a very ‘thirsty’ product that needs a lot of water. Vegans are often accused of contributing to deforestation, too, as forests are razed to make way for soy crops. But in fact, humans only eat six per cent of the soy produced, while 81 per cent goes to feed animals like cows, pigs and chickens.

Studies repeatedly find that veganism is the best diet to follow if you’re concerned about the environment – if we all went vegan, this would reportedly cut food-related CO2 emissions by 68 per cent within 15 years, allowing us to limit global warming to just 2°C. A vegan diet can be good for you, too, reducing high blood pressure and your waistline.

However, going vegan is a big commitment and may not be right for everybody. Find out more about vegan diets and the environment in this article.

How environmentally friendly is being vegetarian?

Vegetarians still eat dairy and eggs, but meat is definitely off the menu. This makes vegetarianism a very eco-friendly diet – Dutch researchers discovered giving up meat could reduce your greenhouse gas emissions by 34 per cent, and a different study found going vegetarian could reduce your water footprint by 55 per cent.

The issue is dairy products, such as milk, cheese and yogurt. The UN’s Food and Agriculture Organization says dairy production is responsible for 1.7 billion tonnes of global CO2 emissions a year, nearly double that produced by aviation (3.4 per cent and 1.9 per cent respectively). And the biggest gas among those emissions is methane.

Methane is released in cow burps and manure, and has 28 times the ‘warming power’ of carbon dioxide. But the dairy industry has a plan. A four-year trial is now taking place in the UK to find out whether feeding cows a daffodil extract can reduce methane production, while Canadian farmers are breeding ‘climate-friendly cows’ that are genetically modified to belch less methane.

If you do decide to go vegetarian, reducing the amount of dairy you consume is a good idea. Or switch to vegan alternatives until low-carbon cows are a reality.

Are high-protein diets bad for the environment?

High-protein diets typically involve eating a lot of meat. The Atkins diet is considered the original low-carb, high-protein diet, and focuses on eating animal proteins like chicken, fish, lamb and beef, while the ketogenic diet, or keto for short, focuses more on eating animal fats. Other high-protein diets include the Dukan diet and the carnivore diet, which both restrict fruit and vegetables, and carbohydrates are almost eliminated.

In addition to the negative impacts on your health, like a severe lack of nutrients, meat-heavy diets have the biggest effect on the environment. New research by Tulane University found keto-style diets had the highest carbon emissions – around 3kg of CO2 for every 1,000 calories – and the lowest health score.

Animal protein is also a very inefficient use of the planet’s resources. Research shows it takes nearly 100 times as much land to produce one gram of protein from beef or lamb compared with peas or tofu. It also takes nearly 15,500 litres of water to produce 1kg of beef compared with 1,670 litres for 1kg of rice!

You can follow a planet-friendly version of Atkins or keto – there are plenty of protein-rich plant foods, while nuts and avocados are rich in healthy fats – but you may need to eat more to get the same amount as from animal sources. On balance, high-protein diets can make you look good in the gym, but not out in the real world.

Is a flexitarian diet eco-friendly?

You may already be following a flexitarian diet; it’s largely plant-based with small amounts of meat, fish and dairy. The Mediterranean diet is a classic flexitarian diet but the Pioppi diet, named after a small Italian village in the Mediterranean, is actually more of a high-protein, low-carb diet.

Flexitarians rarely eat meat, and a new climate study concluded that if big meat-eaters in the UK reduced their intake by half to 50g a day, it would have the same carbon-cutting effect as taking eight million cars off our roads. So, you don’t need to completely give up meat to be more eco-friendly – cutting down is a great place to start.

Mediterranean diets do include fish, but what are the ecological issues around eating it? The UN warns that 90 per cent of the world’s fish stocks are now either overexploited or depleted, but other data reveals ‘wild fish’ catch has stayed roughly the same since the 1990s. However, aquaculture (fish farming) has increased 50-fold.

This means we’re eating more farmed fish than ever before. Aquaculture does have a smaller carbon footprint than beef, but campaigners say we should reduce the number of fish we eat for ethical rather than environmental reasons; it may be just as cruel to keep fish in cages as chickens or pigs.

What about other diets?

The Paleolithic, or Paleo, diet is based on the idea of eating like our ancestors – lots of meat, fish, fresh fruit, vegetables, nuts and seeds, but no grains, legumes, dairy or processed foods. Although it mimics a pre-industrialised way of eating, it doesn’t have a pre-industrial impact on the environment.

Spanish researchers recently compared the Paleo diet with Mediterranean diet, Southern European Atlantic diet and the Spanish dietary guidelines. They concluded the Paleo diet was "an expensive and not nutritionally adequate diet with a high carbon footprint". All that meat means it’s not very eco-friendly in any era.

At the other end of the scale, a macrobiotic diet bans all meat and animal fats, and encourages you to eat plenty of wholegrains, vegetables, seaweed and beans. There are a number of macrobiotic lifestyle ‘rules’ to follow too, such as chewing your food until it liquifies or only using purified water to drink and cook with.

Macrobiotics focuses on organic, seasonal, locally grown produce but the very restrictive nature of the diet means you may miss out on some vitamins and minerals. While it is better for the environment than many other diets, it may not be practical for you. A true eco-friendly diet is one everyone can follow, every day.

How can I eat to help the environment?

There are so many ways you can change your diet to benefit the planet. You could give up meat completely and go vegan, or make a number of smaller changes that all add up. For example, you could give up red meat for just one meal a week – if everyone in the UK did this, it would cut our carbon emissions by 8.4 per cent.

Choosing sustainable foods is good for you and the planet, or you can go one step further and follow the planetary-health diet (PHD). The PHD is the first diet that combines human health benefits with those for the environment. The result is a largely plant-based diet, but one that encourages us to eat a wider range of fruits and vegetables for a greater nutrient intake and to avoid relying on one or two crops.

Eating locally grown, seasonal foods can help reduce our carbon emissions – particularly important after a summer of heatwaves – and going organic means you won’t be contributing to the overuse of pesticides and artificial fertilisers, which often end up in our waterways.

Veganism really is the best way to eat if you’re concerned about the environment, but it does involve a complete change of lifestyle. Going flexitarian (plant-based with small amounts of meat and dairy) may be easier for everyone to adopt – and a diet that enables more of us to ‘eat green’ will have the greatest impact on the planet.

The most sustainable diet is one that you can sustain, both for your health and the environment.

Further reading:

What would happen if everyone went vegan?
How to switch to a vegan diet
What are greenhouse gases?
10 tips for reducing your single-use plastic
The facts about food miles
Mediterranean diet