The Best (and Worst) Diets of 2020, According to Experts

FYI: The keto diet is not number one.

Every year millions of people set health-related New Year's resolutions, so what better time to study up on the best and worst diets of the year?

U.S. News and World Report conveniently drops their annual rankings of the most popular diets a day or so into the new year, and it's a seriously helpful tool for anyone confused about which highly-hyped diet is right for them—and which to stay far away from.

This year, the Mediterranean Diet was crowned winner for the third year in a row, followed by the DASH, Flexitarian, and WW (the diet formally known as Weight Watchers) diets. One of the most popular diets of the last decade, keto, was one of the biggest losers of the year, ranking second to dead last just in front of the Dukan Diet.

No surprise: The best overall diet is the Mediterranean diet.

The Mediterranean Diet, which is rich in fruits and vegetables, healthy fats, and whole grains, and boasts a bevy of science-backed health benefits, was the big winner of the year due to the fact it is " eminently sensible."

"The hallmarks of a 'best' diet include balance, maintainability, palatability, family-friendliness, sustainability, along with healthfulness," explained David Katz, MD, founding director of the Yale University Prevention Research Center and one of 25 judges on the U.S. News and World Report panel. "The Mediterranean diet gets checkmarks in all of those boxes," he said in a press release.

Additionally, Health's contributing nutrition editor, Cynthia Sass, RD, points out that one of the main criteria used to rank diets is research—and the Mediterranean Diet is historically proven to be beneficial and "has long been a gold standard" in terms of proven results for both weight management and health outcomes. "Because the Mediterranean Diet has been a way of life in that region of the world for so long, we have a lot of data about its impact on weight control and chronic disease risk," she explains.

The diet also nabbed the top spot in four other categories, Best Diets for Healthy Eating, Easiest Diets to Follow, Best Diets for Diabetes and Best Plant-Based Diets.

However, if your goal is to get slim quick, the Mediterranean Diet probably isn't going to get you there. It earned its lowest score in Best Fast Weight-Loss Diets.

The Mediterranean-inspired DASH diet (which stands for dietary approaches to stop hypertension), designed to help lower blood pressure and can do the same for cholesterol and blood pressure, and the Flexitarian diet, which is a flexible plant-based "mostly vegetarian" way of eating, tied for second.

WW, the diet formally known as Weight Watchers, nabbed fourth place, (which likely has to do with the number of studies supporting its ability to help people successfully lose weight, suggests Sass) while fifth place was a three-way tie between Mayo Clinic Diet, MIND, and Volumetrics.

Sass is surprised that more plant-based diets—such as vegetarian and vegan—didn't make the top 5, "because research supports their ability to regulate weight and lower disease risk," she explains. "However, I think that research is what allows the flexitarian diet to rank so high, which is essentially a semi-plant based diet."

According to Angela Haupt, managing editor of health at U.S. News & World Report, sustainability played a huge role in selecting the winners.

"We're interested in diets that have proven staying value -- not fad diets that are here today, gone tomorrow," she said in a press release. "The diets that perform well are safe, sensible and backed by sound science. That's going to be consistent from year to year."

One of this year's worst diets (and biggest surprises): keto.

Yep, the high-fat, low-carb diet which has amassed a cult following due to its get-slim-quick promises, ranked second-to-last with experts noting concerns with its emphasis on fat-rich foods.

"This diet is fundamentally at odds with everything we know about long-term health," one expert pointed out. They also noted it is "minimally effective" in both preventing diabetes and promoting heart health, has insufficient evidence supporting long-term weight loss, ("It hasn't been used for weight management long enough to establish a strong track record for helping people lose weight and keep it off long term," says Sass) isn't very nutritious, and is difficult to follow. "Following this eating plan long term is the most difficult aspect of this diet regime," one expert said. "People become very bored just eating fatty foods, fat and meat." Another actually described it as "the hardest of the extremely hard!"

In addition to being difficult to maintain, Sass adds that keto also has the potential to create negative health outcomes, including nutrient deficiencies, and alter the gut microbiome in ways that may increase inflammation and impact immunity and mental health.

The only category where keto fared reasonably well, was Best Fast Weight-Loss Diets, tying for third place.

Other low-ranking diets included the Dukan Diet, Whole30, Atkins, and the Raw Food diet. "The number one thing the five diets at the bottom of the list have in common is a lack of research, either about weight loss outcomes, or their impact on health," Sass points out.

How to choose the right diet for you, based on this list.

While the list ranks all the diets from best to worst, Haupt, pointed out that the list's purpose is for people to take the information and use it to choose a diet that is right for them.

"Whether you're trying to lose weight or improve heart health, diets are not one size fits all," explained Haupt. "The 2020 Best Diets rankings provide consumers with the information and data needed to make an informed decision that helps them—along with input from their doctor or other medical professional—choose the plan that's best for them."

Sass suggests creating your own healthy eating plan, using the guide to educate yourself about nutrition. "The best diet for you may be no diet at all, but instead borrowing from principles of various plans to create a strategy that allows you to lose weight while feeling well physically, emotionally, and socially," she says. "That strategy should also have the ability to become a long term lifestyle, not something you yo-yo 'on' and 'off.'" Most importantly, it should actually protect or improve your health.

"If any diet doesn't check all of these boxes, it will probably fizzle out, leaving you right back where you started. Or you may achieve weight loss at the expense of your physical or mental health, which isn't worth it, and isn't sustainable," she says.

Before you commit to any plan, Sass urges asking yourself if it you can imagine still following it six months or a year down the road, or how you might need to modify it to make it more doable and sustainable for you. "One thing we know about losing weight healthfully and keeping it off is that consistency is key," she points out. "For long term success and optimal health, adopt a new way of eating healthfully, not a short term 'diet,' regardless of what's trendy or popular."

How the rankings are calculated.

To determine the rankings, U.S. News and World Report convened an expert panel consisting of 25 of the country's top nutritionists, dietary consultants and physicians specializing in diabetes, heart health and weight loss. Each of the experts complete an in-depth survey, scoring 35 diets in seven areas, including ease of compliance, likelihood of losing significant weight in the short and long term, and effectiveness against cardiovascular disease and diabetes.

"The fundamentals of sustainable, healthful eating do not change every year, but the ways to get there, the range of variants on that common theme, and the most current evidence all do," explains Dr. Katz. "By pooling the assessments of diverse experts to bundle all of that essential information into a single, user-friendly, and always eagerly anticipated report, U.S. News is providing a unique and genuinely empowering service."

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