While most people don't really care what you've eaten for lunch, Microsoft's Cortana wants to hear all about it.

Fitbit has become the first third-party Windows Phone app to integrate Microsoft's virtual assistant, letting users dictate what they've eaten by voice. Users can activate voice commands by tapping the microphone button at the bottom of the app, then hitting "Start Listening."

The app then taps into a large database of meals, from things you can eat at home to dishes at chain restaurants. You can also create custom meals for easy addition later. All your eating habits appear on a chart, measuring calorie intake against calories burned. Fitbit has also brought over the "Challenges" feature from its other apps, letting users egg each other on with various fitness goals.

Why this matters: Most fitness trackers on the market today don't support Windows Phone, but Microsoft has apparently found an ally in Fitbit, which is going above and beyond what it offers on iOS and Android. It's an interesting partnership, especially as Fitbit is shunning Apple's HealthKit framework for now, and Microsoft is reportedly building a fitness tracker of its own.

Not quite in shape

While Fitbit's Cortana integration could be great, the pre-release software I tried last week had some issues.

For instance, some meals failed to input the proper calorie level when selecting them from the list. Instead, they'd just show up as 1 calorie with 1 gram serving size, forcing me to adjust the levels to reach the proper amount. This was a common error, though it didn't happen all the time.

The bigger problem was that the app confused calorie goals with actual calories burned. Even though I wasn't wearing a Fitbit tracker, and wasn't carrying a Windows Phone around with me, the app still said I was burning thousands of calories per day.

It'd also be nice if Fitbit's use of Cortana extended beyond the app itself, letting you dictate your meals simply by holding down the phone's search button. As it stands, you have to enter the app, then press two buttons to start adding meals. It's not as effortless as it could be.

Still, the idea of bringing Cortana into third-party apps is promising. It's something that neither Apple nor Google are really doing on their platforms. If Microsoft can get more developers on board, it could be the kind of feature that helps Windows Phone stand out.