MFP estimates how much you will burn in a day based on your activity level selection. This estimation includes some daily activity (how much depends on which level you picked) and your BMR.

Fitbit tracks your activity and sends the calorie burn to MFP. If you calorie burn is working out to be lower than MFP's estimation, you lose calories. When I first got a fitbit I was so inactive that I lost calories even though MFP was set to Sedentary.

I want to say around 3k steps from Fitbit is when people start to see a positive adjustment if their activity level is set to Sedentary (if set higher it takes more). You have to remember that MFP already accounts for some of your daily activity and because of that you shouldn't get extra calories for every step you take. You should only get extra when you go above what MFP estimated you would do.

The replies you've already gotten are correct. You'll typically start the day with a negative adjustment. The number of steps it takes to "get into the black" isn't a set number. A full day with only 3000 steps might not ever go positive, if they're spread out over the whole day (or, if you take them all first thing in the morning, you might go positive but then swing back negative later). While only a 1000 or so steps first thing in the morning might tip you into positive territory pretty quickly.

For more understanding, I'd suggest reading the FAQ found in the stickies. Here's a handy link: http://community.myfitnesspal.com/en/discussion/10098937/faq-syncing-logging-food-exercise-calorie-adjustments-activity-levels-accuracy/p1

SuzLink wrote: »

Thanks for the replies guys! :-)

I did a circuits class today & according to my hrm i burned 308 cals, but now i have synces my 2764 steps it has adjuatedit so in total i have only burned 30...... its all very confusing!

Correction - you have only burned 30 calories more than MFP expects you to have burned so far.

That means that while you burned a fair number of calories in your circuits class, you've been very inactive the rest of the day. What activity level do you have selected in MFP? Your MFP activity level should reflect how active during a normal day when you don't exercise. It sounds like, for you, Sedentary would be appropriate if you're below 3000 steps even including an exercise class.

Also, circuit training may not be picked up accurately by a Fitbit, depending on the class (I don't know a lot about circuit training). You might need to log that class manually - preferably in Fitbit, not MFP, because Fitbit is thought to have a better algorithm. However, if you do log it manually in MFP (which is acceptable, especially if you manually enter the calories burned) then the calories for that exercise will be in your "MFP Calories Burned" number, resulting in a smaller Fitbit adjustment.

Again, read the FAQ. It still sounds like you're not understanding how MFP and Fitbit work together.