Guavas    
These sweet, tropical treats contain 112 calories per cup, but don’t let that scare you off. When women add guavas to their daily diet, it doubles their ability to lose weight and to keep it off long-term, say Stanford University researchers. That’s because one cup of guavas contains 40 percent of your day’s supply of appetite-taming fiber. And there’s more -- a tasty cup of guavas contains more immunity-boosting vitamin C than any other fruit or veggie (even oranges), plus over 1,000 International Units of vitamin A -- a nutrient that cuts your risk of skin cancer by as much as 40 percent, according to studies at the University of California, San Francisco.