These are the worst of our 6 most popular diets

How they rate will surprise you

It's time we break down why some of the most popular diets are actually the worst. Image: iStock.

When looking at diets it's often for weight-loss and longevity, but why do we ignore the environmental impacts? It's time we break down why some of the most popular diets are actually the worst.

There are so many diets out there it's hard to keep up. And while one might be perfect for one person, there's a very high chance it's not right for another. 

When we say the "worst" diets, we're looking at it from a holistic point of view. It's not just about the nutritional value or calorie count, it's about the environmental impact too. 

A team of nutrition scientists at Tulane University followed the eating patterns of more than 16,000 American adults over a period of 24 hours and categorised them into six core diets.

They were:

• Vegan - plant based
• Vegetarian - plant based with the addition of animal proteins, minus the meat
• Pescatarian - rich in plant and seafood
• Omnivore - meat-heavy, with elements of the Mediterranean diet
• Keto - high in fat, moderate in protein, low in carbohydrates
• Paleo - high in meat, fruit and vegetables, low in grains, legumes and dairy

Like what you see? Sign up to our bodyandsoul.com.au newsletter for more stories like this.

The results

Of the 16,000 participants, omnivores made up 86.3 per cent of the group, then there were vegetarians at 7.5 per cent, pescatarians  4.7 per cent, vegans 0.7 per cent, keto 0.4 per cent and paleo 0.3 per cent. 

"Climate change continues to be a growing threat to the health and sustainability of the world's populations," the study explained. "The current food system contributes substantially to these environmental problems.

"Of particular interest is how changes in these food systems could contribute to both population health and environmental sustainability in the future, with dietary choices being a key determining factor."

Again, not surprisingly, "Previous research has shown that plant-based diets, such as vegetarian or vegan diets, are responsible for lower greenhouse gas emissions than meat-based diets." 

The study found that the lowest carbon footprint diets were vegan in first place, followed by vegetarian and pescatarian, while the highest footprints were omnivore, paleo and the highest, keto. 

As for diet quality, pescatarian far outweighed any other, followed by vegetarian which was still high, and then vegan. Omnivore and paleo diets ranked at the bottom, just ahead of keto on the healthy eating index.

Pescatarian diets scored better on diet quality but had higher carbon footprints than vegetarian diets. Image: iStock.

Why?

"Keto diets have a higher mean carbon footprint and a lower mean diet quality than other diets, including vegetarian and pescatarian diets. On average, paleo diets also had a higher carbon footprint than vegetarian diets and a lower diet quality score than pescatarian diets," the study explained.

"Both keto and paleo diets have been associated with negative effects on blood lipids, specifically increased low-density lipoprotein cholesterol, raising concern about the long-term health outcomes associated with these diets."

What's more, "These diets tend to be higher in animal foods and lower in plant foods than other popular diets, which could, in part, explain the negative effects on blood lipids and our results on carbon footprints and diet quality."

So there you have it. If you want to eat foods high in nutritional value and save the environment, it's plant-based or bust.

The study found that the lowest carbon footprint diets were vegan at number-one followed by vegetarian and pescatarian. Image: iStock.

Originally published as These are the worst of our 6 most popular diets