The Lose It! app is a fitness and calorie tracker app that I really love. The Apple Watch app is an accompanying app that allows you to quickly add calories or check your daily status discreetly. I had used this app before and decided to try it again while I am attempting to shed my baby weight. It calculates your calories needed to lose, maintain or gain weight, but then also offers an adjustment for personal tweaking
Lose It! – Weight Loss Program and Calorie Counter by FitNow
The Apple Watch accompaniment allows you to add a quick item by just selecting a meal and total calories (the iPhone app has a database of food to search).
It also has a step counter which syncs to your native fitness app.
Being able to add calories quickly and see my total for the day is a huge help and really makes use of what is so great about the Apple Watch!