Food & Nutrition

Low-carbon diet: how it affects the environment and you

Can the foods you eat create environmental change? Read on to find out how a low-carbon diet works to reduce your carbon footprint.

Plenty of us plan our meals to support our health goals, but could we also help the planet while mapping out those menus? These days, many consumers hoping to reduce their environmental impact are turning to “low-carbon” diets that reduce meat and dairy in favour of more plant-based foods.


A low-carbon diet isn’t a new weight-loss fad - you can still enjoy a flexible, balanced eating pattern. There’s really just one main guideline: Choose foods that minimise emissions of greenhouse gases, those atmospheric compounds that contribute to climate change.


“What we eat and how it is produced—as well as food waste we create—all have major impacts on the planet,” says Katharine Wilkinson, PhD, an expert in environmental geography who serves as vice president of Project Drawdown, a nonprofit resource for climate solutions.


While eating a low-carbon diet isn’t a cure-all for complex environmental challenges, a 2016 review published in PLoS One concluded that a broad shift to more sustainable eating patterns could significantly reduce food-related greenhouse gas emissions by 70%—and impart human health benefits as well.


Read on for the lowdown on what it means to eat a low-carbon diet, as well as how this approach can support good health for humans and the planet.


Diet and your carbon footprint


You’ve probably heard about carbon dioxide, the main greenhouse gas proliferated by human activity. It’s the reason many of us refer to our environmental impact as our “carbon footprint.”


Carbon dioxide is actually one of several greenhouse gases in the atmosphere, Dr. Wilkinson says. Other important ones include methane and nitrous oxide. These gases—mostly produced by the burning of nonrenewable fossil fuels, as well as certain agricultural practices—are given the term greenhouse because they trap solar heat that would normally reflect away from the earth’s surface. As a result, the earth gets warmer.


The global food system—which includes everything from farming and grazing to packing and shipping—has a major impact on the environment. It accounts for 21–37% of the world’s total greenhouse-gas (GHG) emissions, according to a 2019 report from the United Nations Intergovernmental Panel on Climate Change.


Different foods vary in the amounts of greenhouse gases they generate on their way to your plate. Food waste is a factor, too. Research published in the journal Science in 2018 ranked the four biggest determinants of carbon footprint in the food realm. Here’s a closer look, in order of least to most impact.


1. What you eat


Among popular protein sources, ruminant animals such as cattle, lamb, and goat by far have the highest impact per gram of protein in terms of GHG emissions, according to a scorecard developed by the World Resources Institute. The reasons: These animals, in addition to emitting methane during digestion, require vast feed production, feed transport, and land conversion, all of which drive GHGs. As for other protein sources: Pork, poultry, and dairy are ranked at medium impact, while fish is in the low-impact category with beans and eggs.


2. How much ends up in the garbage


The Australian Government’s National Food Waste Baseline Report, published in March 2019, revealed that over 7.3 million tonnes of food waste was generated in 2016–17. Once discarded food ends up in landfills, it releases greenhouse gases as it decomposes.


3. How much processing is required


The more steps needed to prepare a food product for sale, the higher the food’s carbon impact generally is, notes registered dietitian Caroline Passerrello. For example, apple slices in sealed plastic generates a greater quantity of greenhouse gases than whole apples shipped to a supermarket the same way, she says.


4. How—and how far—your food travels


Speaking of shipping, that matters, too. The farther food travels via any given mode of transport, the more GHG emissions result from the use of fuel, says Eugene Cordero, PhD, a professor in the department of Meteorology and Climate Science at San Jose State University. Air-freighting—used for only a small fraction of the food supply, but worth noting—has the highest carbon impact of all shipping methods. Boat transport has the lowest, with trucks and trains in the middle.


What is a low-carbon diet?


A low-carbon diet is really about food awareness, says Dr. Cordero. Low-carbon diets generally emphasise nutrient-dense, plant-based foods—including legumes, whole grains, vegetables, fruits, and nuts—and minimise foods derived from animals, especially red and processed meat. Again, the goal is to make food choices that minimise GHG emissions, not to eliminate certain foods entirely


These general practices align with the plant-based eating approach supported by many health experts, Dr. Cordero adds. The EAT-Lancet Commission, a coalition of 37 scientists from 16 countries, wrote in a 2019 report published in The Lancet that plant-based eating can be “good for both people and planet.”


Five goals of a low-carbon diet


Once you know the factors that contribute to GHG emissions in the food supply, this will empower you to make informed decisions as to the food choices you make. Weaving even a few of these ideas into your routine can help lessen your carbon impact, experts say.


1. Reduce your intake of meat and dairy


While going vegan or vegetarian is a personal decision, it’s definitely not a necessity. Passerrello supports a piecemeal approach, too. For instance, try setting aside one night a week for a meatless meal, or switch from beef to a lower-impact protein source such as chicken in a favourite dish. You could even try reducing the portion of meat on your plate by substituting a percentage with plant-based proteins such as beans, lentils or chickpeas. On a sandwich, plant-based spreads like guacamole and hummus make delicious alternatives for cheese.


When only a beef cheeseburger will satisfy, sourcing ingredients from small, local farms that permit natural grazing may help mitigate the greenhouse impact, says Kelly Jones, a registered dietitian. “You are supporting a more sustainable means of agriculture,” she notes, as large factory farms may overproduce animals and source feed from far away.


2. Purchase only what you’ll eat


Passerrello is a fan of weekly meal planning for keeping food out of the bin. Planning provides a roadmap for grocery shopping that prevents you from buying random stuff that’ll just sit in your fridge, she explains. In the event you find yourself stuck with a surplus of soon-to-spoil perishables, do a recipe search for ways to use them up. Or, buy yourself some time and move items to the freezer to be enjoyed later.


For certain kitchen scraps and foods past their prime, home composting may be something to consider, Dr. Wilkinson says. Compost can enrich soil to help your garden grow and reduce methane emitted by landfills. Some local councils offer discounts for purchasing composting equipment, so check with yours to see whether you can save some money.


3. Choose foods that are minimally processed


Elaborate packaging and production processes generally raise the output of greenhouse gases, Dr. Wilkinson says. A box of snack crackers, for example, requires the manufacture of an interior plastic bag, a cardboard box, printing ink, and adhesive—on top of the ingredients and commercial food equipment needed to make the crackers themselves. “Every bit of plastic or paper or foil we produce takes resources and carbon emissions,” Dr. Wilkinson says. “Anytime we can get food that is closer to the way it came out of the ground, the better off we’ll be.”


4. Eat locally produced foods


Focusing on food that’s grown close to home helps cut down on the GHG emissions of commercial transport. Signing up for a community-supported agriculture program may be one way to score fresh picks from nearby. Shopping at a farmers market and buying from small businesses in your community are other ways to reduce the carbon footprint of your diet. When shopping in a supermarket check the food label and shop Australian when possible.


Of course, you can’t get more local than your own backyard. Check out our guide for advice on starting your own herb-and-veggie garden.


5. Shop for the season you're in


Seeking out your region’s signature foods at their peak of deliciousness is basically a way to nudge yourself to eat more locally, Jones says. If you live in an area with distinct seasons, this may require changing up your diet throughout the year.


As a bonus, buying food soon after it’s harvested—often the case when shopping seasonally and locally—helps maximise its shelf life at home, Jones says. Another plus, seasonal foods often go on sale as suppliers work to sell off their bounty. To find out what’s in season near you, use the search tool at Seasonal Food Guide Australia.