There are 2.3 million iPhone users in the United States. Are you one of them? If so, make your iPhone work a little harder for you: According to Woman's Day magazine, 869 of the more than 1,700 applications available to iPhone users from iTunes are health related. Losing weight? Getting fit? Trying to eat right? There's an application out there for you and your iPhone.

To save you time, Woman's Day did the legwork for you. They went out and found the 10 best diet and fitness iPhone applications in the iTunes store. Here are some of my favorites:

iWatchr: If you've ever tried Weight Watchers, then you know all about counting points. Rather than carrying that little slide-y scale WW gives you, download iWatchr. Look up point values and keep track of them all in one handy place.

GoodFoodNearYou: Eating out and eating right don't always go hand-in-hand. GoodFoodNearYou helps you find the healthiest choices based on your location, making eating out while away from home a snap. Best of all? This application is free.

deftFitness: "I'd love a good workout today," you're thinking. "But I'm not sure where to start." Log in to deftFitness and choose one of 30 different exercises at three levels of intensity (Don't Hurt Me, I Can Take It and Bring it On!).

B.iCycle: Is cycling your workout of choice? Map your rides right on your iPhone, and track time, distance and speed. You can even watch your real-time progress, though we recommend keeping your eyes on the trail, not your iPhone.

Do you use a diet or fitness-related iPhone application? Share it with us in comments!