The keto and paleo diets were discovered to be the least sustainable and received the lowest diet quality scores among the six popular diets that were analyzed.
This may be difficult for those following the keto or paleo diets to swallow.
According to a recent study from Tulane University, which evaluated the nutritional quality and environmental impact of popular diets, the keto and paleo diets, as consumed by American adults, received the lowest scores for overall nutrition quality and had the highest carbon footprints.
The keto diet, which prioritizes high amounts of fat and low amounts of carbs, was 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 next lowest diet quality score and also had a high carbon footprint, at 2.6 kg of carbon dioxide per 1,000 calories.
The study, published in The American Journal of Clinical Nutrition, compiled diet quality scores using data from more than 16,000 adult diets collected by the CDC’s National Health and Nutrition Examination Survey. Individual diets were assigned point values based on the federal Healthy Eating Index and average scores were calculated for those eating each type of diet.
The study’s senior author Diego Rose, professor and nutrition program director at Tulane University School of Public Health and Tropical Medicine, said that while researchers have examined the nutritional impact of keto and paleo diets, this is the first study to measure the carbon footprints of each diet, as consumed by U.S. adults and compare them to other common diets.
“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,” Rose said.
Vegan Diets Lead in Sustainability, Pescatarian Tops Nutrition
On the other end of the spectrum, a vegan diet was found to be the least impactful on climate, generating 0.7 kg of carbon dioxide per 1,000 calories consumed, less than a quarter of the impact of the keto diet. The vegan diet was followed by vegetarian and pescatarian diets in increasing impact.
The pescatarian diet scored highest on nutritional quality of the diets analyzed, with vegetarian and vegan diets following behind.
The omnivore diet – the most common diet, represented by 86% of survey participants – sat squarely in the middle of the pack of both quality and sustainability. Based on the findings, if a third of those on omnivore diets began eating a vegetarian diet, on average for any given day, it would be equivalent to eliminating 340 million passenger vehicle miles.
Notably, however, when those on omnivorous diets opted for the plant-forward Mediterranean or fatty meat-limiting DASH diet versions, both carbon footprints and nutritional quality scores improved.
Toward Healthier and More Sustainable Eating
“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,” Rose said. “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.”
A 2021 United Nations-backed study found that 34% of greenhouse gas emissions come from the food system. The major share of those emissions come from food production, with beef being responsible for 8-10 times more emissions than chicken production and over 20 times more emissions than nut and legume production.
While the environmental impacts of specific foods have been studied extensively, Rose said this study was important because “it considers how individuals select popular diets that are composed 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 would different policies affect outcomes and how could those move us toward healthier, more environmentally friendly diets?” Rose said.
Reference: “Popular diets as selected by adults in the United States show wide variation in carbon footprints and diet quality” by Keelia O’Malley, Amelia Willits-Smith and Donald Rose, 1 March 2023, The American Journal of Clinical Nutrition.
DOI: 10.1016/j.ajcnut.2023.01.009
The study was funded by the Wellcome Trust.
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21 Comments
The importance of the so-called Carbon Footprint depends on the climate sensitivity, or the temperature change caused by a doubling of CO2. There is little agreement on this. The nominal value accepted for 30 years has been 3 deg C per doubling. However, more recent analyses suggest that it may be 1 deg or less.
It is poor form to evaluate a ‘carbon footprint’ based on a fundamental metric for which there is great uncertainty.
These kinds of diet analyses seem to be motivated typically by some kind of ideological motivation which invariably ignores the fact that cows can be raised on marginal land that is unsuitable for agriculture, and that cows take themselves to water.
More junk “science” based on other junk “science”…incredible how poorly written and researched this article is.
This is now outdated and misleading since the “federal Healthy Eating Index” is about to radically change.
Also, to be fair, the reduced carbon footprint from people’s improved health & lower weight would need to calculated, then compared to the carbon costs claimed here, to see the net cost/benefit.
Please stop this propaganda bs..
Vegetarian food has rarely any nutrition whichbis usabable and mono culture of grains corn and soy are way more detrimental to the environment than cows and sheeps on a pasture..
So glad people here in the comments don’t buy this leftist bullshit..
smh
Another nonsensical “study”… These diets are significantly healthier than traditional eating habits, especially if you follow cleaner approaches. There are even Mediterranean and vegetarian versions of keto. These “experts” tend to overgeneralize the worst perceptions of these diet plans frequently assuming the most illogical absurdities.
Oh boy, here comes the agenda bias.
There is ZERO real science that says anything about a well balance “paleo” diet being at all a risk to health—quite the contrary.
More trash biased research.
So many flaws.
1. Does this study look at the effect of regenerative agriculture? It’s a way of raising cattle that is carbon neutral.
If the government stopped subsidizing grains and started subsidizing regeneratively raised cattle, it would help the planet and the people…. Plus, healthier and happier (right up until they go to the slaughterhouse) cows, produce tastier, healthier meat.
2. Does this study look at monocropping, which completely destroys topsoil?
3. People always talk about the effects of methane from cows… Yet grass-finished cattle produce less methane. Plus people on keto diets (with no processed/fake foods) tend to produce less methane than vegans, vegetarians and omnivores.
4. This study claims low carb diets are nutrient poor and vegan diets are nutritionally superior… Yet vegans need to supplement B12 and DHA, and some will be deficient in essential amino acids, Vitamin D (which is hard to synthesize or absorb without dietary cholesterol), Vitamin A (since many cannot properly convert beta-carotene into retinol), etc….
A person on a low carb diet can get every nutrient the human body requires from 12 ounces of red meat, an ounce of liver, a few ounces of high quality cheese, a few eggs, some low carb veggies and a glass of lemon water…. And you can reduce (possibly eliminate) the environmental damage by choosing regeneratively raised meat and getting all of your ingredients from a local farm.
Admittedly, you might be low in Vitamin E and Magnesium (as most people on any diet – including vegan and vegetarian – are) and you might be able to fix that with avocado.
But every time you eat something that does not grow near you, you (and the people who ship those foods) are contributing to climate change, so that solution isn’t helpful if you live in one of the areas that are nowhere near any locally grown avocados.
I could continue….
These propagandists want you dead! Don’t think a true thing was said in the whole article. Love the comments though, keep doubting these goblin “scientists”, believe the opposite and you’ll be on the right path
No one cares about the effect on climate, how did the actual diet work? Lol
And no explanation as to why the keto diet is nutritionally inferior.
I’d love to see the “evidence” that shows eating a bunch of junk food on a typical American diet is somehow nutritionally superior to a well-thought-out keto diet. There are zero examples of the food each of these diets consists of, just “keto and Paleo aren’t good for you”.
Obvious bias in this article as the author clearly considers the carbon footprint to be far more important than the health of people.
There is research that shows the weight lost on keto is muscle loss through gluconeogenisis. Meanwhile, a regular calorie restricted diet led to more fat loss. Your brain needs 130g of carbs per day to function. The recommendation on keto is 30g per day. Your body will break muscle down and convert that protien into glucose. Your body is going to get what it needs one way or another. Honestly, the best diet is a well balanced one with both meat and plants from natural sources. Vegans are also full of it. We are omnivores, and its stupid to not act like it out of ego. People need to understand that we are a species of animal that evolved a certain way. You can’t change evolution because you want to be trendy.
Well apart from all the instant arguments raised in these comments – those who do not wish to give up their beloved foods always argue that what they are doing is perfectly fine becos…. those of us who have been trying to get the balance right over many years get fed up with the competing ‘facts’ and worry about what to change & in the end we decide to just do a reasonable take on this stuff & try not to go overboard on any one concept. Hence I’m semi-vegan ie a little chicken or tuna or an egg a couple of times a week, and lots of beans & mushrooms in between. I absolutely HATE uncooked greens of any kind so hiding them in something is how I eat those with lots of soups & stews containing any & all drowned in great flavor ! I stay away from ANY sweet stuffs so as to keep my appetite from remembering yummy things – even vegan recipe sites give far more sweet recipes than savory !!! Reduced my bad cholesterol way down after my Doctor said no way to do that ! Ha ! I think we in the West are more in danger from too much food than anything else, so moderation is the best thing !
You are lucky that your cholesterol came down. I have pretty much the same diet as you but no eggs and I do eat some sweets, but also I eat lots of fresh greens and fruits. It had zero effect on my cholesterol which is still way too high. I’m also having MORE health problems than when I was eating more meat.
I’m seriously disappointed in #scitechdaily” with this article!!! Is there anything we CAN do correctly? Pick on the big greedy corporations and stick to sharing the latest health discoveries. For the love of gawd!!
“This may be difficult for those following the keto or paleo diets to swallow.”
Indeed, they vomited all over the comments section before they could even read the actual study that provides the answers to their questions.
For the rest of you, the study is based on a massive diet study of ‘typical’ US diets. I.e. it’s statistical and average, as all large data studies are. The health scores are based on two standard systems and they discuss the nuance between them in the journal article.
For more detail, read the study or at least ask ChatGPT to summarise it for you.
Yet another example of propaganda dressed as supposed science. Enough is enough.
I hate when Science sites use the phrase ” Study shows” like it’s a pretense for some kind of hard truth. People need to remember that scientific studies are oftentimes not hard truth. Sadly there’s a lot of Fu*kery going on behind the scenes. Manipulation of data. And massaging results, or highlighting results that are they want.
I’m not some anti science weirdo, I love science! hence why this article showed up in my Google news feed. But I also know the shocking reality behind a lot of “scientific studies” so it just urks me when science sites use that word like it’s a pretense for some kind of stamp of unwavering approval of information. I wish scientific research could be wholly trustable, as it should be. But keep in mind that it’s still controlled by humans and they will always be fallible, and driven by things that will cause them to manipulate their data.
Keep in mind that I am not saying this above article is not to believed, I don’t know if it is or not. My issue is more with the headlines sense of absolute certainty. Which you always get with headlines from science websites.
You can’t possibly be serious? You place the SAD diet filled with grains, overly processed non-foods filled with industrial seed oils, weed killer and highly addictive sugar over a whole food diet consisting of meat, veg, healthy real fats, and some berries? Lets just keep feeding our kids lucky charms because we can just put them Ozempic for life. They can continue to sit in front of their video games, never go outside and chow down on Cheetos and Oreos. What a shame that a diet that has been shown to alleviate mental health disorders and can literally reverse type 2 diabetes is being maligned like this. Is your hand in the pocket of big food and big Pharma as well?
The whole premise that climate change and carbon footprint is perhaps the most pressing problem of our current times is FALSE. There’s no emergency, the planet is not dying, it even got greener in recent years. This pseudo scientific paper only serves to promote a political agenda, to slowly convince people to accept social credit score / carbon credit score system, and maybe guarantee some grants on the side. Stop evaluating and judging human activity through carbon footprint! Nobody cares about that! Plants love our carbon, and we love healthy, natural, diverse food which we evolved to eat. What we care about is pollution. We don’t want a poisoned planet with toxic chemicals and heavy metals in the food chain, air and water. F-off with the vegan agenda to justify big food and big agriculture with harmful GMOs. And a big NO to insect diet. Yes, I’m talking to you WEF, Gates and everyone you fund or support. F-off! Get off our planet, you anti-human, pandemic-promoting scum!
If it is grown by a plant eat it. If it is made in a plant, throw it away.