My understanding is that on the main screen is your total daily allowance, not including future exercise, this is just your BMR. BMR + Exercise completed as you exercise. When you click on the title it gives you real time amount.
So on the main screen you have 415 left to eat after eating 817 so far for the rest of the day and if you exercise, this number will adjust and you'll get more calories to eat for the entire day. This number eaten plus calories left is mostly your BMR plus any exercise completed for the entire day.
When you click on it, it says you have eaten 817 calories so far and burned 1345 (BMR + Exercise, if any), which at this very point in time is 15 calories over budget (for whatever goal you have set), but as time passes or you exercise, you'll accumulate more calories to eat, and this will become green or blue depending on how much you eat.
I have been tracking what I eat with Fitbit for a few weeks and I find this feature really helpful.
I hope my explanation made sense...if it's not accurate, someone please correct me 🙂
