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 for weightloss.

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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. And that weight stays off—a recent British study found that for people who had lost large amounts of weight, those who consumed a Mediterranean-style diet were twice as likely to keep it off. "This diet is easy to maintain

weightloss, because the food is delicious!" says Beaver.

There are several different ways to do intermittent fasting, but they are all based on choosing regular time periods to eat and fast. For instance, you might try eating only during an eight-hour period each day and fast for the remainder. Or you might choose to eat only one meal a day two days a week. There are many different intermittent fasting schedules.

Mattson says that after-hours without food, the body exhausts its sugar stores and starts burning fat. He refers to this as metabolic switching.

“Intermittent fasting contrasts with the normal eating pattern for most Americans, who eat throughout their waking hours,” Mattson says. “If someone is eating three meals a day, plus snacks, and they’re not exercising, then every time they eat, they’re running on those calories and not burning their fat stores.”

Intermittent fasting works by prolonging the period when your body has burned through the calories consumed during your last meal and begins burning fat.