U.S. News & World Report on Thursday released its Best Diets for 2020 ranking, with the Mediterranean diet ranking No. 1 for the third consecutive year.

Your guide to a healthier, happier 2020

How US News picks the best diets

For the Best Diets 2020 ranking, U.S. News reporters and editors "winnow[ed] potential additions" to the rankings and then used government reports, medical journals, and other resources to create profiles for the 35 diets that made the final list. Each profile explains:

• How the diet works;
• Whether it lives up to its claims;
• Possible health risks; and
• What it's like to live on the diet.

A panel of nutrition, diet, obesity, and food psychology experts reviewed each diet profile and rated the diets on seven criteria:

1. Potential for short-term weight loss;
2. Potential for long-term weight loss;
3. Ease of compliance;
4. Nutritional completeness;
5. Potential to prevent heart disease;
6. Potential to prevent diabetes or serve as a maintenance diet for diabetics; and
7. Safety.

Once the panelists rated all of the diets, U.S. News converted those ratings into scores and stars, using a five-point scale—with 5 being the highest score and 1 being the lowest score. Based on the scores, U.S. News ranked the diets in nine categories:

1. Best Diets Overall;
2. Best Commercial Diets;
3. Best Weight-Loss Diets;
4. Best Diabetes Diets;
5. Best Heart-Healthy Diets;
6. Best Diets for Healthy Eating;
7. Easiest Diets to Follow;
8. Best Plant-Based Diets; and
9. Best Fast Weight-Loss Diets.

Best Overall

The diets that rounded out the top five on the Best Overall list are:

• The Mediterranean Diet, which ranks No. 1 for the third consecutive year. According to research, the diet—which is inspired by the observation that people in the Mediterranean live longer, healthier lives—can prevent chronic diseases and increase longevity, U.S. News reports. The diet is low in sugar, red meat, and saturated fats, but high in vegetables, nuts, and fruits.
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• The Flexitarian Diet, which tied for No. 2 this year. The diet is designed to promote weight loss, overall health, and longevity by having people eat mostly—but not completely—vegetarian. The diet emphasizes fruits, vegetables, and whole grains, and is considered easy to follow, making it a "very reasonable, sound, healthy eating plan" that is supported by research, according to the expert panelists.
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• The Dietary Approaches to Stop Hypertension (DASH) Diet, which also ranks at No. 2. The DASH Diet combats and prevents high blood pressure and diabetes. Expert panelists ranked the diet highly for its nutritional completeness and ability to support heart health.
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• The WW (Weight Watchers) Diet, which ranks at No. 4, is considered the best diet for overall weight-loss. The WW Freestyle program assigns point values to foods and beverages based on their nutritional values.
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• The MIND Diet, which tied with two other diets at No. 5, was created to prevent cognitive decline and promote brain health by increasing the intake of leafy greens, berries, and nuts. 
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• The Volumetrics Diet, the second diet to rank at No. 5, is aimed at weight loss. The diet places an emphasis on low-density foods, which are low in calories but can be consumed in high volume. Preciously, U.S. News has described the diet as follows: "Volumetrics is all about getting more mileage out of what you eat."
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• The Mayo Clinic Diet, which also comes in at No. 5. On the Mayo Clinic Diet, people follow a unique food pyramid that emphasizes fruits, vegetables, and whole grains. It is also one of the best diets for diabetes, according to the panelists.

Overall, the expert panelists recommend "well-balanced," non-restrictive diets that are sustainable over a lifetime. For instance, "lifestyle diets," such as the MIND Diet and Mayo Clinic Diet, are healthier and more sustainable than diets that stress weight loss, such as Atkins or the Ketogenic diet, according to the panelists.

Top diets across all categories

The No. 1 diets on the other Best Diet rankings were:

• The Mediterranean Diet, which ranked as No. 1 on the Best Diets for Healthy Eating, Easiest Diets to Follow, Best Diets for Diabetes, and Best Plant-Based Diets lists;
• The WW Diet, which ranked as No. 1 on the Best Commercial Diets and Best Weight-Loss Diets lists;
• The HMR Diet, which ranked as No. 1 on the Best Fast Weight-Loss Diets list; and
• The Ornish Diet, which ranked as No. 1 on the Best Heart-Healthy Diets list ("Best Diets," U.S. News & World Report, 1/2; U.S. News & World Report release, ­­­1/2; U.S. News & World Report methodology, 1/2).