These trendy diets are the least healthy way to lose weight

By Mark Waghorn via SWNS

Trendy keto and paleo diets are the worst way to lose weight, according to new research.

They have the lowest nutritional quality - and are also bad for the planet, say scientists.

Pescatarians, who stick to fish, fared best - closely followed by vegetarians and vegans.

People who use keto cut out carbs such as bread, pasta, potatoes or rice - eating plenty of protein instead.

It puts the body into a state where it relies on fat for energy - called 'ketosis' - that occurs during starvation or fasting.

The paleo only comprises foods which could have been hunted, fished or gathered in caveman days.

They include meat, fish, eggs, nuts, seeds, fruit, vegetables, herbs and spices.

Both cut out processed products like cakes, pastries, biscuits and crisps.

Celebs such as Gwyneth Paltrow, Halle Berry and Kim Kardashian have all tried the Keto diet, while Miley Cyrus and actress Uma Thurman have taken up the Paleo diet.

Senior author Professor Diego Rose of Tulane University in New Orleans, La., said: "We suspected the negative climate impacts because they are 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."

The first study of its kind found the keto and paleo contain the least vitamins.

They also had the highest carbon footprints - generating almost 3 and 2.6 kg of carbon dioxide for every 1,000 calories consumed, respectively.

A vegan diet was found to be the least impactful on climate at 0.7 kg - less than a quarter the keto's diet. It was followed by vegetarian and pescatarian diets.

The study in The American Journal of Clinical Nutrition was based on a survey of more than 16,000 adults in the U.S.

Individual diets were assigned point values based on the federal Healthy Eating Index. Average scores were calculated for those eating each type of diet.

Omnivores - who eat meat and vegetables - were the most common group, represented by 86 percent of participants.

They sat squarely in the middle of the pack for both quality and sustainability.

If a third became vegetarian for any given day, on average, the U.S. team worked out it would be equivalent to eliminating 340 million passenger vehicle miles.

But when they opted for the plant-favored Mediterranean or fatty meat-limiting DASH diet versions, both carbon footprints and nutritional quality scores improved.

Prof. Rose said: "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.

"Based on our results, that would reduce your footprint and be generally healthy. Our research also shows there is a way to improve your health and footprint without giving up meat entirely."

The UN says a third of greenhouse gas emissions come from the food system. Beef, in particular, is responsible for up to ten and over 20 times more than chicken and nuts, respectively.

Prof. Rose said the study was important because "it considers how individuals select popular diets that are composed of a wide variety of foods."

Going forward, he still has questions about how to encourage eating habits that are better for people and the planet.

Added Prof. Rose: "I think the next question is how would different policies affect outcomes, and how could those move us toward healthier, more environmentally friendly diets?"