FitBit Flex and calories

So I love my fitbit! It confirmed for me my horrible sleep cycles and that I wasn't moving enough! However I'm at a loss as how a VSG patient is to use it to track calories. Can someone shed some light for me. Dumb it down, I'm not the sharpest tool in the shed.

Try using the my fitness pal app, it works with the fitbit. I use it to track calories & it more easily lists the carbs, protein, fat, calories, etc than the fitbit app. In the fitbit app the only way to track where your calories are coming from is to go into the nutrient portion of every piece of food that you eat & write it down & add it up.

If you do use the my fitness pal app, input everything into that app only, it will sync up with the fitbit app info. I use the fitbit to track my steps & sleep, & the mfp for food & exercise. Hope this helps.