Emma Loewe

mbg Sustainability + Health Director

By Emma Loewe

mbg Sustainability + Health Director

Emma Loewe is the Senior Sustainability Editor at mindbodygreen and the author of “Return to Nature: The New Science of How Natural Landscapes Restore Us.”

Image by Nadine Greeff / Stocksy

March 9, 2023

Most of us, Warrior Dieters and OMAD-ers aside, eat at least three times a day. That puts us in a position to make food decisions roughly 21 times a week, 90 times a month, and 1,095 times each year (and that’s not even including snacks!). Deciding what to eat can get downright overwhelming, especially with all the conflicting information out there about what’s “healthy” and “sustainable” and what’s not.

In an effort to simplify things, a new study in the1 American Journal of Clinical Nutrition1 measured the carbon footprint and health quality of the six most popular eating patterns in the U.S. to find the ideal diet for both metrics.


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The best diets for your health and the planet.

For this study, a team of nutrition scientists at Tulane University analyzed data on the eating patterns of more than 16,000 American adults over 24 hours, using nationally representative NHANES research data. They then placed each person’s diet into one of six buckets. From popular to least, they were: omnivore (86.3% of participants), vegetarian, pescatarian, vegan, keto, and paleo (0.3% of participants).

The criteria for each diet type were pretty liberal. Participants technically fell into the vegetarian camp, for example, as long as they consumed less than ~15 grams of meat, poultry, and seafood a day.

Researchers assessed each diet against the 2010 Healthy Eating Index (HEI)2 and the Alternate Healthy Eating Index (AHEI) to see how they aligned with U.S. dietary guidelines. Then, they estimated the environmental impact of each diet using a food carbon emissions database.

Here’s what they found after crunching the numbers:

  • The vegan diet ranked highest for sustainability, producing the least amount of carbon dioxide (0.7 kg of carbon dioxide per 1,000 calories consumed).
  • The pescatarian diet had the highest average health score, followed by the vegetarian diet.
  • The keto (3 kg of carbon dioxide per 1,000 calories consumed) and paleo diets (2.6 kg of carbon dioxide per 1,000 calories consumed) ranked lowest in both sustainability and diet quality.


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The keto diet, which is high in fat and low in carbs, and the paleo diet, which is low in grains, processed foods, and refined sugar, had three to four times the carbon emissions of the vegan diet. This isn’t surprising when you consider that both keto and paleo tend to be more meat-forward and less legume-based eating patterns. The overall environmental impact of meat from ruminant animals (cows, sheep, goats) is about 100 times that of plant-based foods according to some estimates, due in part to the way these animals digest. And the legumes that both diets eschew have nitrogen-fixing qualities3 that make them beneficial for soil and ecosystem health.

While the health scores should be taken with a grain of salt—and they differed depending on the index used in some cases—it makes sense that a diet that is healthy for the planet tends to be pretty good for us, too.

“Climate change is arguably one of the most pressing problems of our time, and a lot of people are interested in moving to a plant-based diet,” Diego Rose, Ph.D., MPH, the senior author of the study, said in a statement. “Based on our results, that would reduce your footprint and be generally healthy. Our research also shows there’s a way to improve your health and footprint without giving up meat entirely.”

How to apply these findings.

If you’re following a keto-style eating pattern and loving it, or you feel your best when you’re strictly paleo, there’s no need to completely revamp your diet. However, this study is a good reminder that our food choices have a bearing on our overall emissions. And making a few swaps can go a long way in reducing our environmental impact and improving our health. Here are a few to consider:


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Eat one less serving of red meat a day or week.

In previous research conducted by Rose4, when participants who had the least sustainable diets made just one sustainable food swap a day, it reduced their diet’s overall daily carbon and water footprint by up to 48.4%. Swapping out one serving of red meat can have the most impact, and plant-based proteins, mushrooms, and chicken are all lower-impact alternatives. Eating smaller portions of meat per meal is also a step in the right direction. “The American idea is that you have the main protein item as the center of your plate, but in a lot of cultures, the meats or the fish is used in a sauce,” Rose previously told mindbodygreen for an article about sustainable diets.

In addition to low-impact crops like legumes and mushrooms, seaweed is another food source with seriously sustainable potential. As the marine plant grows, it captures carbon, provides storm protection, and supports other aquatic life. You can incorporate the healthy sea veggie into your cooking or consume it in a concentrated powder like mindbodygreen’s organic veggies+, a USDA-certified organic blend of organic leafy greens, root vegetables, berries, and more in every tasty scoop. Veggie powders can be incorporated into soups, added to smoothies, and sprinkled onto salads for a quick hit of sustainable nutrition.


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Waste less and compost what’s left.

Sustainability isn’t just about what you’re eating; what you’re not eating matters too. Minimize your food scraps using these handy cooking tricks, and responsibly dispose of any remaining food with this beginner’s guide to composting.

The takeaway.

New research found that the paleo and keto diets scored the worst for both their carbon footprints and health quality. Eating healthily and sustainably is far from black and white, but take this as your daily reminder to consider the planet every time you load up your plate.

If you are pregnant, breastfeeding, or taking medications, consult with your doctor before starting a supplement routine. It is always optimal to consult with a health care provider when considering what supplements are right for you.