How the Keto Diet Compares to Greener Eating, in Two Charts

The keto diet requires a high-fat, low-carb diet.

  • The researchers ranked six popular diets based on their environmental impact and nutritional value.
  • The keto diet had the largest average carbon footprint and the lowest nutritional ranking.
  • Vegan, vegetarian, and pescetarian diets had the best health outcomes.

The keto diet, a low-carb, high-fat diet scorned by nutritionists, isn’t just bad for your body, according to recent research, it’s also bad for the environment.

Researchers at Tulane University ranked six popular ways to eat, including the keto diet, based on their average nutritional value and environmental impact. Their findings, published March 1 in The American Journal of Clinical Nutrition, showed a correlation between a healthy diet and low carbon emissions.

Although the study did not address all dietary trends, the researchers looked at the daily diets of more than 16,000 adults surveyed between 2005 and 2010. Then they divided the individual data into six diet groups: keto, paleo, vegan, vegetarian, pescetarian. , and omnivorous.

They found that the average keto consumer generates almost 3 kg of carbon dioxide per 1,000 calories consumed, which is four times the carbon footprint of a similarly sized vegan plate.

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“Climate change is arguably one of the most pressing issues of our time, and many people want to switch to a plant-based diet,” said lead author Diego Rose, director of the nutrition program at the Tulane University School of Public Health and Tropical Medicine. , said in a press release. “Based on our findings, this would reduce your footprint and be generally healthy.”

Plant-based food has a lower carbon footprint


Food systems account for more than a third of global greenhouse gas emissions, according to a UN-backed study published in 2021.

Going keto requires dieters to consume about 70% of their calories from fat and almost no carbs, so many dieters opt for animal products that are high in fat and protein.

Beef production is a major driver of carbon emissions. So the researchers weren’t surprised that the keto diet had the largest carbon footprint of the diets studied.

The keto diet was followed by the paleo, a diet based on what humans were supposed to eat before agriculture. The diet eliminates grains and legumes in favor of lean meats; fruits, vegetables, nuts and seeds are also making an appearance on the paleo plate. The old diet was associated with 2.6 kg of carbon dioxide per 1,000 calories consumed.

At the other end of the spectrum, the vegan diet was associated with the lowest amount of greenhouse gas emissions. Other low-emission diets were vegetarian and pescetarian diets.

How to eat healthier for your body and the environment

Most of the people surveyed were described as omnivores, meaning they eat a combination of plants and animals. The omnivorous category was eventually classified as an intermediate option for nutrition and sustainability. But not all omnivorous diets are created equal.

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Omnivores who ate a Mediterranean diet – which requires a colorful mix of vegetables, fruits, whole grains, healthy fats and lean proteins – ranked higher in nutritional quality and had a lower carbon footprint than other members of the group. So was the DASH diet, a heart-healthy diet that limits red meat consumption.

Pescatarians, who eat fish but no red or white meat, scored highest on the Healthy Eating Index, a measure that assesses the overall nutritional value of a daily diet. However, the environmental impact of cutting out meat and fish altogether cannot be underestimated, according to the study.

While personal food choices don’t impact the environment on an individual level, a massive shift to a meatless diet would be good for the planet. The authors concluded that if just one-third of the omnivores in the study started following a vegetarian diet, it would be equivalent to eliminating 340 million passenger vehicle miles in an average day.

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