Green tea. Whether you prefer it hot or iced, unsweetened green tea is calorie-free and high in an antioxidant called ECGC, which may reduce the risk of heart disease and some cancers while revving up your metabolism
Leafy greens. Whatever variety you pick, you can't go wrong with piling a plate with salad greens. The American Journal of Clinical Nutrition found that eating 3 ounces of the peppery green daily increases levels of the cancer-fighting antioxidants lutein and beta-carotene.
Citrus Fruits. Fruits like grapefruit have been shown to help us burn fat and keep our metabolism high. This could be related to the fruits’ high amount of vitamin C, a helpful and healthful component that reduces insulin spikes.
Red bell pepper. Any way you slice it, red bell peppers are a great source of nutrients. A medium-size one delivers 250 percent of your daily recommended intake of vitamin C, 75 percent of your daily vitamin A needs and 10 percent of your fiber goals. Chop them up and pair with hummus for a healthy snack.
Mashed Cauliflower. Try boiling, mashing and seasoning cauliflower to get a mashed potato substitute that tastes almost like the real thing. A half-cup of boiled cauliflower contains only 14 calories, but nearly half your daily recommended intake of vitamin C.
Chili peppers. Hot Peppers. Jalapeno, habanero, cayenne and other forms of spicy peppers directly boost metabolism. Chili peppers contain capsaicin, a chemical compound that can kick metabolism into higher gear, Dr. Isaacs says. He suggests adding a tablespoon of chopped chili peppers to a meal once a day. Chili peppers are also an unexpected source of vitamin C.