Sustainable diet: Everything you need to know

The EAT-Lancet Commission, a group of scientists from 16 different countries, addressed the existing evidence surrounding the planet’s food demands, waste, and overall diet.

According to the Commission, food production is the world’s largest cause of environmental change. They note that vegan and vegetarian diets have the greatest reduction in land use and greenhouse gas emissions, and that vegetarian diets use the least water.

Their research notes that a universally healthful reference diet includes increasing consumption of:

• vegetables
• fruits
• whole grains
• nuts
• legumes

Meanwhile, a person eating sustainably will eat low amounts of or no:

• refined grains
• added sugars
• red meat
• processed foods

As well as changing the environment with land clearing and other farming practices, food production has a major impact on greenhouse gases.

According to the World Health Organization (WHO), food production accounts for 20–30% of global greenhouse gas emission and up to 66% of water usage.

Although a varied diet is crucial to human health, a truly sustainable diet will also focus on the health of the environment.

A sustainable diet takes into account the impact it will have on the environment, the individual, and the food chain as a whole. Factors that determine how sustainable a certain diet is include:

• nutritional availability
• relative cost
• biodiversity
• ecosystem protection
• general health

Considering all these factors should help ensure that the planet can continue to provide enough food and resources for a growing population and future generations.

Some eating plans already adhere to these guidelines more than others, so following them may be a simple way to make the diet more sustainable. Diets that are more sustainable than the standard Western diet include:

Vegetarian and plant-based diets

The EAT-Lancet Commission note that vegetarian and plant-based, or vegan, diets are more sustainable than those that contain meat and other animal products. The Commission note that switching animal products for plant-based ones had environment and health benefits.

They state that:

“Overall, studies concur that plant-based foods cause fewer adverse environmental effects per unit weight, per serving, per unit of energy, or per protein weight than does animal source foods across various environmental indicators.”

As a study in the journal Global Environmental Politics notes, animal products such as meat, dairy, and eggs are common topics of conversation when considering sustainable diets.

This is because these animal products have a few significant impacts to consider, including:

• land use
• water use
• greenhouse gas emissions

In 2014, the Food and Agriculture Organization of the United Nations noted that livestock in general make up 14.5% of all human-induced emissions. Reducing the impact of this livestock by reducing the need for it and improving farming practices can help lower this impact.

Some farms are now working on composting animal waste for fertilizer use and capturing methane gas to supply the energy needs of the farming operation.

Animal foods can still have a place in a sustainable diet, though there is no agreement on how much of any one animal food a person can eat and still be sustainable.

In general, a diet higher in plant foods is more sustainable than a diet higher in animal products.

The issue is complex, with many contributing factors, including:

• land use
• overfishing
• methane production from farm animals
• water usage to grow crops to feed livestock

For example, farming an acre of corn for human consumption means that all that food can go directly to feeding a growing human population.

For people who eat animal products, the same acre of corn would go toward feeding livestock. However, the animals themselves also take up additional land and resources. So, farming animal foods requires significantly more land.

Learn more about the health benefits of plant-based diets in this article.

Local food diets

Local food diets focus on eating foods from the area in which a person lives.

Depending on where a person lives, however, these diets can take significant planning to implement. People in northern regions, where fewer fruits and vegetables grow, may need to take extra steps to ensure that they get enough nutrients.

The idea behind local food diets is that they reduce the “food miles” necessary for produce and other foods to reach supermarkets.

This type of diet emphasizes eating seasonally, and many people may also choose to buy from organic local farms.

That said, there have so far been few studies into the impact eating locally on the environment, and some research even suggests that local eating has no environmental or health benefits compared with eating nonlocal food.

However, some possible benefits for the environment include:

• reducing the need for transporting food long distances
• reducing food packaging and waste, as the produce does not have to last as long
• reducing resources necessary to grow food that is out of season

Flexitarian diet

The flexitarian diet puts the focus on plant foods but is also “flexible,” meaning that people can include animal products sparingly.

The aim of this diet is to reduce the environmental impact an individual has by reducing their consumption of:

• red meat
• fish
• dairy
• packaged foods

A sustainable flexitarian diet could still include these products, just in smaller amounts, while keeping the focus on whole plant foods.

However, there is no consensus on how many animal products a person can eat in a given time while being sustainable.

A flexitarian diet is likely a good choice for a person’s overall health, too. Research into sustainable diets has found that people who follow vegetarian, vegan, pescatarian (which are diets that include fish but no other meat), and semi-vegetarian diets have an overall 12% lower mortality risk than people who eat meat.

Learn more about a pescatarian diet and the differences between vegan and vegetarian diets here.

As with most dietary changes, many people find the switch to a more sustainable diet easier if they approach the process step-by-step.

Making a huge change all at once may be difficult, and it may lead to a person reverting back to their old diet if they cannot keep up with the changes.

For people looking to reduce their intake of animal products, one simple way is to set aside one day of the week to eat only plant products, such as the popular “meat-free Monday” initiative.

Alternatively, people can try slowly eliminating foods, starting with the least sustainable. The Environmental Working Group ranked which protein sources contribute the most to greenhouse gases in a report on animal products and sustainability.

In order of the least sustainable options, the top five were:

• lamb
• beef
• cheese
• pork
• farmed salmon

In their report, the Environmental Working Group included emissions from post-production processes, such as transport.

People concerned about sustainability may wish to cut out the most unsustainable products in their diet first.

Learn more about becoming a vegetarian here.

Generally, switching to a sustainable diet has little to no risk. If a person takes some conscious steps to ensure that they meet all their nutritional needs, reducing the intake of animal products and increasing the intake of plant foods can still cover all their nutritional requirements.

The sections below discuss the specific nutritional elements of switching to a more sustainable diet.

Fruits and vegetables

Fruits and vegetables have a very low environmental impact, though there are some exceptions.

According to the Centers for Disease Control and Prevention (CDC), only 1 in 10 people in the United States eat enough fruits and vegetables. Increasing the intake of whole fruits and vegetables is a healthful choice for most people.

Meat

Meat typically has a high environmental impact. Although it is rich in calories, protein, fats, and micronutrients, consuming excess red meat can be a risk factor for developing serious health problems, such as heart disease.

Eating less meat as part of a balanced diet is in line with overall health.

Dairy

Milk and other dairy products also have a high environmental impact. However, they are an important and affordable source of key nutrients, such as calcium and vitamin D, for many people.

That said, it is possible to reduce dairy intake and still maintain good health. People can talk to a doctor or dietitian about getting enough nutrients, or they can read about nondairy sources of calcium in this article.

Fish

Fish generally has a high environmental impact, too, as many fish stocks are now depleted due to overfishing and other unsustainable practices.

However, fish is also a good source of key nutrients and healthful fats. Reducing fish consumption or eating from sustainable sources can help reduce the environmental impact.

Packaged foods

Packaged foods contribute to waste and plastic use. Many packaged foods are also processed, such as sugary snacks, and they may provide little dietary nutrition as a result.

Reducing or eliminating packaged food can help a person reduce waste and contribute to their overall health.

Dietary sustainability is not clear-cut. The general guidelines include reducing the consumption of meat, dairy, fish, and packaged foods.

A sustainable diet focuses on higher intakes of whole plant foods. People may still choose to eat animal products, but in much lower quantities.

Anyone considering making the switch to a more sustainable diet should consider what diet they would be likely to stick to, and try making small steps first.