Chili peppers
"Chilis stimulate the metabolism, act as a natural blood thinner, and help release endorphins," says Gunnar Petersen, certified strength and conditioning specialist and a celebrity trainer. Plus, they're a great way to add flavor to food without increasing fat or calorie content. Chilis are also rich in beta-carotene, which turns into vitamin A in the blood and fights infections, as well as capsaicin, which inhibits neuropeptides (chemicals that cause inflammation). A recent study in the journal Cancer Research found that hot peppers even have anti-prostate-cancer properties. All this from half a chili pepper (or one tablespoon of chili flakes) every day.