The most important parts of the Fourth of July are the fireworks and the food! This year, Rena Karefa-Johnson has great recipes to give your Independence day barbecues and picnics a healthy twist, from low-fat grilled watermelon salad and watermelon mint cocktails to baked red, white and blue beet and potato chips and a patriotic popsicle made with yogurt, blueberries and strawberries.