Now's the perfect time to close out the summer barbecue season. It's still warm and staying light longer -- so why not spend time outside instead of in the hot kitchen? Barbecued food is mostly healthful, but there are a few ways you can amp up its nutrition and flavor. Before the meat hits the grill, inject a ton of flavor with a vibrant, low-calorie marinade. Some bold flavors include Worcestershire sauce, which has just 30 calories for 2 tablespoons; chili sauce contains just 40 calories for two tablespoons, and soy sauce adds just 20 calories per 2 tablespoons. A large, resealable plastic bag is a perfect way to marinate meats and vegetables. Use a fork to perforate the meat and pour on the flavor, then squeeze out extra air to immerse the food in the marinade.