The keto and paleo diets were found to be the least sustainable and received the lowest diet quality scores among the six popular diets analyzed.
This can be hard to swallow for those following keto or paleo diets.
According to a recent study from Tulane University, which assessed the nutritional quality and environmental impact of popular diets, the keto and paleo diets, as consumed by American adults, received the lowest scores for quality. overall nutrition and had the highest carbon footprints.
The keto diet, which prioritizes high amounts of fat and low amounts of carbohydrates, is estimated to generate almost 3 kg of carbon dioxide for every 1,000 calories consumed. The paleo diet, which eschews grains and beans in favor of meats, nuts and vegetables, received the second-lowest food quality score and also had a high carbon footprint, at 2.6 kg of carbon dioxide per 1000 calories.
The study, published in THE
The study’s lead author, Diego Rose, professor and director of the nutrition program at Tulane University’s School of Public Health and Tropical Medicine, said that although researchers looked at the nutritional impact keto and paleo diets, this is the first study to measure everyone’s carbon footprint. diet, as consumed by American adults and compare them to other common diets.
“We suspected negative climate impacts because they’re meat-centric, but no one had really compared all of these diets — because they’re chosen by individuals, rather than prescribed by experts — to each other. using a common framework,” Rose said.
At the other end of the spectrum, a vegan diet was found to have the least impact on the climate, generating 0.7 kg of carbon dioxide per 1,000 calories consumed, less than a quarter of the impact of the diet. keto. The vegan diet has been followed by vegetarian and pescatarian diets with growing impact.
The pescatarian diet obtained the best results in terms of nutritional quality of the diets analyzed, followed by vegetarian and vegan diets.
The omnivorous diet — the most common diet, represented by 86% of survey participants — fell squarely in the middle of the quality and durability pack. Based on the results, if one-third of people on an omnivorous diet started eating a vegetarian diet, on average for any given day, that would be equivalent to eliminating 340 million passenger vehicle miles.
Notably, however, when those following an omnivorous diet opted for plant-based Mediterranean versions or DASH limiting fatty meat, carbon footprints and nutritional quality scores improved.
“Climate change is arguably one of the most pressing issues of our time, and many people want to switch to a plant-based diet,” Rose said. “Based on our results, it would reduce your footprint and be generally healthy. Our research also shows that there is a way to improve your health and your footprint without completely giving up meat.
A study supported by the United Nations in 2021 found that 34% of greenhouse gas emissions come from the food system. The bulk of these emissions come from food production, with beef being responsible for 8-10 times more emissions than chicken production and more than 20 times more emissions than nut and pulse production.
Although the environmental impacts of specific foods have been studied extensively, Rose said this study was important because “it considers how individuals select popular diets comprised of a wide variety of foods.”
Going forward, Rose still has questions about how to encourage eating habits that are better for people and the planet.
“I think the next question is how different policies would affect outcomes and how might they move us towards healthier and more environmentally friendly diets?” Rose said.
Reference: “Popular diets selected by adults in the United States show wide variation in carbon footprint and diet quality” by Keelia O’Malley, Amelia Willits-Smith, and Donald Rose, March 1, 2023, The American Journal of Clinical Nutrition.
The study was funded by the Wellcome Trust.