I don't think there is one currently for FitDay.
In your case, I would look for apps that run on Windows Mobile 6 OS.
For iPhone owners, there's an app called LoseIt. LINK
DISCLAIMER: I am NOT an expert in nutrition, fitness, or exercise. Any advice given is only meant to be helpful based on what information I've gathered, and should not replace any medical treatment or any other true advice you may get from another source. Take it with a grain of salt, and then log that in your Foods tab!