What apps are good for rapid weight loss?

Several are good. First a caution, rapid weight loss is not as sucessful long term as steady weight loss. So go to your app market on your smart phone and look at the free "wieght loss" apps. "calorie counter" is a good one. If you stay in the free apps, focus on diet and nutrition and avoid extremes you should find several that can suport you as you diet, decrease fast carbs, calories and exercise.