Originally Posted by merlinextraligh

thus, if you take 1 KJ = 1.1 dietary calories, you'll be in the middle of that range and about as close as you're going to get, without doing lab testing to find your personal efficiency.

For government work, just using 1kj=1 calorie is close enough, easy, and likely understates calorie burn slightly, which is probably good if you're tracking this for weight loss purposes.