What Makes a Healthy Diet?

Not all diet plans are nutritious and safe. U.S. News rankings rate each diet’s healthiness.

Best Diets 2014 -- Pear with measuring tape around it
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If you have reservations about a diet's nutritional content or safety, listen to your body. Fatigue, sleeplessness, dizziness, aches – they're all red flags. Says Fernstrom: "Losing weight is for good health, so you should feel more vital – not bad."

[See: 11 Health Habits That Will Help You Live to 100.]

Updated 01/07/2014: This is an updated version of a previously published story.