The Mediterranean diet is again named the best diet for 2021, and keto remains one of the worst
INSIDER 2hrs ago
Crystal Cox/Insider © Crystal Cox/Insider Crystal Cox/Insider
  • For the fourth year in a row, US News & World Report ranked the Mediterranean diet the best overall diet since it's easy to follow, evidence-based, and nutritionally balanced. 
  • The eating pattern, which has been linked to longevity, emphasizes fruits, vegetables, whole grains, nuts, seeds, and even moderate red wine intake. 
  • Restrictive diets including keto, "modified keto," Whole30, and Dukan landed at the bottom of the list for being nearly impossible to follow long-term and nutritionally incomplete. 
  • Noom was one of the newly included diets in the 2021 rankings, which some experts applauded for its behavior-change approach to weight loss. 
  • Visit Insider's homepage for more stories.

Every year, US News & World Report ranks the best diets for the year ahead. In 2021, for the fourth year in a row, the Mediterranean diet - a plant-based, non-restrictive eating pattern shown to help prevent chronic diseases and improve longevity - was named the overall best diet.

A panel of nutritionists and specialists in diabetes, heart health, and weight loss made the Mediterranean diet their top pick out of 39 eating plans, including trends like the keto diet and commercial options like Weight Watchers, Atkins, and Jenny Craig.

This year, panelists considered four diets that haven't been included in past rankings: The Noom Diet, the Autoimmune Protocol (AIP) Diet, the Gut and Psychology Syndrome (GAPS) Diet, and the Modified Keto Diet. 

The rankings were based on seven categories in which each diet was rated on a scale from one to five. Categories were nutritional completeness, how easy the diet is to follow, the potential for long- and short-term weight loss, the safety and possible side effects, and the potential to help prevent illnesses like heart disease and diabetes.

The Mediterranean diet was named not only the overall best diet, but the best for healthy eating (along with DASH), the easiest to follow, the best for diabetes (tied with the flexitarian diet), best plant-based diet, and best heart-healthy diet (tied with DASH). Overall, broad eating patterns like the flexitarian diet topped the list, while restrictive diets like keto remained at the bottom.

"It's not a surprise when you look at the top three or top five diets ... the one thing they all have in common is that they're rich in fruits, vegetables, whole grains, healthy fats," expert panelist Kathy Beals, a registered dietitian and associate clinical professor at the University of Utah, told Insider.

a group of oranges on a table: Crystal Cox/Business Insider © Crystal Cox/Business Insider Crystal Cox/Business Insider

The Mediterranean diet is high in fresh fruits and vegetables and low in red meat and sugar

The concept of the Mediterranean diet comes from the countries that border the Mediterranean Sea, where people historically ate mainly produce, nuts, and healthy fats. The Harvard School of Public Health and a think tank called Oldways created a diet based on the general eating principles of these places, according to US News & World Report.

Many of these areas are part of the so-called blue zones, regions of the world where people tend to live the longest, healthiest lives.

The Mediterranean diet relies heavily on seafood, fresh produce, whole grains, nuts, and seeds. People on the plan can also enjoy wine in moderation.

These foods are rich in vitamins as well as important nutrients like fiber and polyphenols, plant-based compounds that help protect against disease. As such, the diet has been found to help reduce the risk of diabetes and may protect against certain types of cancers as well as cognitive decline.

It can even help with weight loss by cutting out high-calorie processed foods and refined sugars in exchange for more nutrient-dense alternatives like veggies and fish.

Since the diet focuses on heart-healthy fats like olive oil, avocado, and salmon, it also could lower bad cholesterol, a major cause of heart disease, according to the Mayo Clinic.

The University of Iowa's Cardiovascular Risk Service said that the diet "discourages saturated fats and hydrogenated oils (trans fats), both of which contribute to heart disease."

The Mediterranean diet doesn't restrict calories or include rigid meal-planning, which helps make it easier to follow and be among the safest diets in terms of unwanted side effects. However, this may also be a drawback for people looking for a more structured eating style or trying to lose weight quickly.

a plate of food with a green bowl on a table: Crystal Cox/Business Insider © Crystal Cox/Business Insider Crystal Cox/Business Insider

Restrictive diets like keto, Dukan, and Whole 30 ranked low on the list yet again 

Video: 6 Plant-Based Protein Foods When You Want a Vegan Protein Option (Better Homes and Gardens)

Diets that were were ranked low overall by US News & World Report were those that were considered difficult to sustain in the long term and nutritionally unbalanced. These include the high-fat, low-carb keto diet, which was ranked 4th, along with the Biggest Loser Diet and OPTAVIA, for short-term weight loss, but 37th overall. 

The newly included GAPS diet, a diet that requires followers to eliminate grains, pasteurized dairy, starchy vegetables, and refined carbs, tied with keto in 37th place. Proponents claim the diet is a natural treatment conditions that affect the brain, like autism.

"I sort of get uncomfortable when they try to make claims that a certain food is going to a cause of disease ... or removing a food is going to cure a disease," Beals said. 

The Dukan Diet, a high-protein, low-carb plan, landed at the very bottom of the list, as it's heavy on rules and could risk kidney damage.  

And the month-long, highly restrictive Whole30 diet, which cuts out all grains, sugars, breads, desserts, alcohol, dairy, legumes, and processed foods, is not only difficult to follow, but not backed by science, and experts continue to be skeptical of it.

This year, it tied with "modified keto," a less restrictive version of keto, for 35th. 

"That is an oxymoron," Beals said. "For you to be in the degree of ketosis for keto, it has to be very low carbohydrate, low protein, super, super high fat, and anything other than that is not keto. So you can't have a modified keto."

The behavior-change program Noom stood out to some panelists 

The Noom Diet, which focuses on behavior change, tied with Jenny Craig for the No. 3 spot on

the Best Commercial Diet list and the No. 12 spot for Best Overall Diet. Some experts gave it high marks due to its built-in support network and behavior-change approach to weight loss. 

Beals wasn't one of them. 

"I understand that they're trying to approach it from a behavioral standpoint," she said. "However, I get uncomfortable when there's a behavioral weight-loss program that isn't run by people with degrees in psychology, kind of like I get uncomfortable with people counseling others on weight loss who aren't registered dietitians." 

Other sustainable and inexpensive eating habits, continue to be highly ranked by experts, especially due to the pandemic 

Other standouts this year again included the flexitarian and DASH diets. 

Though the name sounds like it's designed for bodybuilders, the flexitarian diet actually refers to a flexible eating style: sticking to mostly plant-based foods, while allowing high-quality animal products in moderation.

The DASH diet, which stands for Dietary Approaches to Stop Hypertension, encourages eating less sodium and more nutrient-rich foods that can help lower blood pressure and improve overall health. 

The two tied for second in the "best overall" ranking; the flexitarian tied with Weight Watchers for best (long-term) weight-loss diet, and the DASH tied with Mediterranean as the best diet for healthy eating. 

This suggests that fad diets will continue to be just that - a passing trend - while confirming what the experts have known for years: that the best diet is the one you can stick to.

"One of the questions that they ask is: Is the diet easy to follow. And when I think of ease to follow, I also think, is it affordable?" Beals, who consults for Potatoes USA and noted that potatoes are nutrient-dense, inexpensive, and shelf-stable. 

"That's something I think we need to consider when we think about eating plans not just in the time of pandemics when money is tight, but really any time." 

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