1 Mediterranean Diet

Based on the heart-healthy lifestyle of Greece, Italy, Spain, and Portugal, Mediterranean-style diets include healthy fats such as avocados, olive oil, nuts, and fish at least twice a week, plenty of beans, fruit, leafy greens, and whole grains, and even a daily glass of red wine. You can eat cheese in moderation, but limit the red meat to once or twice a week.

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How it works for weight loss: Though this diet's primary appeal is in its numerous health benefits—it can lower your risk of both chronic disease and cognitive decline—it can also lead to weight loss if you limit your calorie intake to 1,500 a day or less. Studies have found that following either a traditional Mediterranean diet or a low-carb version of it can result in weight loss of about 5-10% of body weight over 12 months. "This diet is easy to maintain, because the food is delicious!" says Amanda Beaver, RD. a dietitian at Houston Methodist.