Fitbit flex

Maybe I can help.

Normally, when you use MFP you give your stats (height, weight, age, gender) and state your activity level such as sedentary, lightly active, etc. From those details MFP estimates how much you'll burn per day without logging any exercise. Lets assume for this example, that # is 2400. You say you want to lose 1 pound a week, so MFP tells you to eat 1900 per day. This is all based on the assumption you use the correct activity level and burn the same # of calories every day. Its the best MFP can do on its own.

When you use an activity tracker, it uses your stats and your movement (# of steps and frequency of steps) to estimate your total daily burn. Say today you actually burn 1900 and tomorrow you actually burn 2050. It won't be the same every day because your movements are not identical day to day.

So now how they work together... When you connect a tracker and you sync them, then MFP gets data on what you've burn so far today. Remember the 2400 per day example? MFP expects you to burn 2400 per day or 100 per hour. Lets say you sync at noon, and Fitbit says you've actually burned 1100 so far. MFP looks at that, and says: wait a second. I thought you'd be at 1200 now but you're only at 1100. You're behind by 100. If you have negative calories enabled, this will take 100 away from your daily allowance. If not, it will be a 0. If at noon you sync and Fitbit says you've burned 1350, MFP sees you are ahead of schedule by 150 so you've earned an extra 150.

The thing to be aware of: this is constantly changing. Maybe you're at 1350 at noon, but then you're sitting for 5 hours and and at 5pm you're at 1750 burned so now you're only 'up' by 50. The thing I suggest, to look at your Fitbit app occasionally. If you set your Fitbit profile (thru the website dashboard) to sedentary and have your weight loss goals the same on Fitbit and MFP, then the app will tell you how many calories you have left to eat for the day. Move enough so that # is what you need/want. Such as right now my app probably says I have only 1100 total for the day. I've hardly moved. Will walk at lunch time and some more this evening and ultimately will 'earn' the 1500-1600 that I'll eat today.