Eating back work out calories?

You can assume that the numbers the treadmill gives you are probably wildly optimistic. A saner way to estimate net calories expended walking .30 x weight (in lbs) x distance (in miles) ie 30 cal per mile for every 100lbs you weigh. For running it's the same formula except the factor is .63 (or 63 cal per mile for every 100lbs you weigh) This formula would be on the low side if you were walking or running on a high incline.

Second part of the equation is how accurately you are logging your intake. If you are diligently measuring, weighing and logging every morsel that passes your lips and your activity level is set at sedentary on MFP then you should be able to eat back almost all of your (correctly calculated) exercise calories.

In the real world few people do this which is why many will recommend eating 50% to 75% of your exercise calories and keeping an eye on what your weight loss results are and adjusting accordingly.

Another way to do it is to calculate your TDEE and the subtract 15% or 20% and just not log your exercise (again, there's a certain amount of trial and error, log you food and adjust as needed)

Losing weight is a matter of burning more calories than you consume (CICO, Calories In- Calories Out). MFP is set up to measure your calories in by tracking your food and estimating your calories out by 1) you activity level 2) the exercises you log. Yes, the accuracy of calories burned may be inaccurate—BUT ITS NOT ZERO. Those who say they don’t eat back their calories fall into a few categories 1) they don’t exercise enough were it matters and is effectively included in their level of activity 2) they are tracking their intake of calories so bad that their error in not tracking exercise calories corrects for it 3) they are losing faster than they should. Also, the TDEE method inherently has you eating back your calories so it doesn’t apply.