Try it out: www.tannerkrewson.com/calorie-countdown
Out of all of the projects I have programmed, Calorie Countdown is probably the one I have used the most. I used it daily at the dining halls on my college campus. It works the best for restaurants that are all-you-can-eat and have calorie counts on display for each dish. Its purpose is to make sure you eat a certain number of calories for a single meal. It very simple and there is almost nothing to it; it's basically a glorified calculator with an interface that makes more sense for this use case than an actual calculator.