Explaining Calorie requirments
 

How does fit day come up with how many calories my body needs on a daily basis?

I am 6'. 180 lbs and spend most of my day at my desk. Fitday says I require 3002 calories, other websites say closer to 2300.

The difference between the 2 calorie requirements can be how it is calculated based on your average daily activity level. A sedentary person will require less calories than someone who works 8 hours manual labor for instance. Plus age and gender also comes into play. If you are older I think above say 35 its said the Miflin scale is a better one to use on here.

You can change to the Miflin scale by going to the Activities tab, then choosing the Customize Metabolism. You can even set a custom number.