Leafy Greens

Kale: At 34 calories per raw chopped cup, this dark leafy green will barely make a dent in your daily calorie count—but because it's full of antioxidants, it can make a big difference in your health. Plus, one study found that women who ate a diet filled with water-rich produce such as kale lost 23 percent more weight than those who didn't. Experts say those foods fill you up better than other picks, quashing the urge to nosh later.
Eat it: Sautéed in 1 teaspoon olive oil.

Spinach: Raw spinach contains a mere 7 calories per cup. Plus, a cup of fresh spinach contains almost 200 percent of the daily recommended vitamin K, which helps improve bone health.
Eat it: Added to sandwiches for extra crunch.