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Comparing Popular Diets: The Environmental Impact of Keto, Paleo, and Vegan Diets

A 2021 United Nations-backed study into the environmental impact of food systems revealed that 34% of greenhouse gas emissions were generated by the food system, with beef production responsible for eight to 10 times more emissions than chicken production and over 20 times more emissions than nut and legume production.[0] Now, a team of researchers led by Tulane University have used data from more than 16,000 adult diets collected by the CDC’s National Health and Nutrition Examination Survey to examine popular contemporary diets – such as the keto, paleo, vegan, or omnivorous diets – in terms of their nutritional quality and environmental impact.[0]

This study, led by Diego Rose, professor and nutrition program director at Tulane University School of Public Health and Tropical Medicine, is the first to measure the carbon footprints of keto and paleo diets as consumed by U.S. adults, and compare them to other commonly-consumed diets. Previous research has examined the nutritional impact of these diets.

It was estimated that, with its high fat and low carb focus, the keto diet would generate almost 3 kg of carbon dioxide for every 1,000 calories consumed.[1] The paleo diet – which includes meats, nuts, and vegetables while avoiding grains and beans – had the second lowest diet quality score and the highest carbon footprint, at 2.6 kg of carbon dioxide per 1,000 calories.[1] The vegan diet was found to have the lowest carbon footprint, while a pescatarian diet was the best in terms of nutrition.[2]

Interestingly, when those with omnivorous diets chose the plant-based Mediterranean or fatty meat-restricting DASH diet plans, both the carbon footprints and nutrition scores increased.[3]

Diego Rose, the senior author of the study, noted that, while the nutritional impacts of keto and paleo diets have been studied before, this is the initial examination of the carbon footprints of these diets as consumed by U.S. adults and how they compare to other diets.

He added: “We suspected the negative climate impacts because they’re meat-centric, but no one had really compared all these diets—as they are chosen by individuals, instead of prescribed by experts—to each other using a common framework.[4]

0. “Study reveals the environmental impacts of various diets”, 1 Mar. 2023,

1. “Keto and paleo diets branded “least sustainable” in study” New Food, 2 Mar. 2023,

2. “The carbon footprints of six popular diets – so how does YOURS stack up?” Daily Mail, 1 Mar. 2023,

3. “For People Who Are On Keto Or Paleo Diets – This May Be A Bitter Pill To Swallow” Revyuh, 1 Mar. 2023,

4. “Two trendy diets hailed by celebs found to be the ‘worst ways' to lose weight” Daily Record, 1 Mar. 2023,

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