No. 10 (tie): Vegetarian diet
The vegetarian diet is simple: no meat allowed. Ideally, meat is replaced with other sources of protein, as well as fiber-packed veggies, fruits, and whole grains to help keep you feeling full.
Unlike a vegan diet, which ranked 19th on the US News & World Report list, vegetarians can eat animal products like milk and eggs, which can be good sources of protein.
More on what US News & World Report experts thought of this diet »
No. 10 (tie): The fertility diet
The aim of the fertility diet is to help women who are having problems getting pregnant. Developed by Drs. Jorge Chavarro and Walter Willett of the Harvard T.H. Chan School of Public Health, the fertility diet includes 10 science-backed steps to help boost fertility in women. The steps emphasize eating vegetable proteins and oils and drinking whole milk. The plan also suggests taking a multivitamin that contains folic acid.
The diet was named one of the easiest to follow.
More on what US News & World Report experts thought of this diet »
No. 9: Ornish diet
Developed by Dr. Dean Ornish, this diet looks at food on a "spectrum," with some things being healthier than others — essentially, the less processed the better. The diet emphasizes whole grains, fruits, vegetables, and some types of fatty foods containing omega-3 fatty acids.
The diet was ranked one of the best for heart health.
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No. 8: Mayo Clinic diet
Developed by the well-known research group in Rochester, Minnesota, this diet is all about breaking bad habits and replacing them with good habits. For example, a person might ban eating in front of the TV and snack only on fruits and vegetables. In the first part of the diet, which lasts two weeks, you may lose 6-10 pounds because of the new habits, the diet claims. The diet comes with its own food pyramid that puts fruits and vegetables at the bottom.
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No. 5 (tie): Volumetrics diet
Volumetrics is a diet developed by Penn State University nutrition professor Barbara Rolls. It categorizes foods based on density, with less dense foods — like soups or vegetables high in water — preferred over more dense ones, like pizza, cookies, and butter.
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No. 5 (tie): TLC diet
The TLC diet, which stands for therapeutic lifestyle changes, focuses on lowering a person's cholesterol. It emphasizes eating less saturated fat — avoiding foods like chicken with the skin on it, butter, and cheese — while eating more fruits, vegetables, skinless chicken, fish, and low-fat dairy products.
More on what US News & World Report experts thought of this diet here »
No. 5 (tie): MIND diet
The MIND diet, which claimed the No. 3 spot last year, focuses on foods that help your brain — specifically those said to prevent neurological diseases like Alzheimer's. Berries, olive oil, nuts, and dark, leafy greens are staples of the diet, based on large-scale studies of cognitive decline.
The plan is a hybrid version of the Mediterranean and DASH diets (both of which ranked higher), and focuses on the aspects of those two diets that have to do with the brain.
More on what US News & World Report experts thought of this diet »
No. 4: Weight Watchers diet
After making some changes to its program, Weight Watchers has risen through the US News & World Report's rankings over the past two years.
Weight Watchers still uses its signature points system, and in December 2017, the organization introduced its new "Freestyle" program, and deemed eggs a zero-point food, along with whole beans, peas, and almost 50 kinds of fish.
"Very few people come to Weight Watchers because they’ve had a problem overdoing it on salmon, legumes, beans, and chicken," Gary Foster, Weight Watchers' chief scientific officer, previously told Business Insider. "Someone might think 'OK I’m eating salmon, no sweat on that. If I’m eating chocolate cake, I know I still have to measure that.'"
The Weight Watchers diet ranked as the best diet for weight loss.
More on what US News & World Report experts thought of this diet »
No. 3: Flexitarian diet
The flexitarian diet, developed by the registered dietitian Dawn Jackson Blatner, rose through the rankings in 2018 to the #3 spot. It's geared toward those who are interested in being vegetarian but don't want to give up meat entirely. It asks dieters to add "new meat" to their diets, like protein-packed tofu, beans, lentils, nuts, and eggs. But if you crave meat once in a while, it's not a big deal.
The diet ranked as the second easiest to follow.
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No. 1 (tie): DASH diet
For the eighth year in a row, the DASH diet was named the best (though this year the top slot was a tie). DASH stands for dietary approaches to stop hypertension. Otherwise known as abnormally high blood pressure, hypertension is a common condition in the US.
The diet involves lowering your sodium intake to no more than 2,300 milligrams a day and eating vegetables, fruits, and whole grains. (For reference, a single slice of pizza contains about 640 milligrams of sodium, roughly a quarter of that sodium limit.)
"The DASH diet is really a safe plan for everyone," Angela Haupt, assistant managing editor of health at US News & World Report, told Business Insider in 2016. "There's nothing exciting about it, and that's what makes it a good plan. It's not some fad diet making outlandish claims that you can't rely on."
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No. 1 (tie): Mediterranean diet
The Mediterranean diet is modeled on foods commonly eaten in countries along the Mediterranean Sea. It's typically high in fruits, vegetables, fish, and whole grains like whole wheat and brown rice. Studies have linked the diet with a number of health benefits, including a reduced risk of heart disease and breast cancer. Some research has suggested the diet could also have potential memory-related benefits.
US News & World Report named the plan the best plant-based diet of the 40 considered, and it was deemed the easiest to follow.
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Lastly, these were the worst diets.
While the high-fat, low-carb ketogenic diet may be taking Silicon Valley by storm, US News & World Report ranked it last, tied with the protein-filled Dukan diet.
"The Dukan Diet is too restrictive, and there’s no evidence it works, experts concluded," US News wrote.
The panelists had concerns about the safety of the ketogenic diet, though it did rank relatively high for short-term weight loss.
Another popular diet, Whole30 also fell toward the bottom of the rankings, coming in at 37. The panelists said the program — which requires dieters to eat only natural, whole foods for 30 days — lacks scientific evidence and is severely restrictive.
"This is the antithesis of a long-term healthy dietary pattern,” one expert said.
Learn more about what experts think of the Whole30, Dukan, and Keto diets.
