Self-tracking devices like the Fitbit do a fair, if imperfect, job at measuring how much you move and then inferring how many calories you’ve burned in a day. But they don’t measure how many calories ...

“For me, a calorie is a unit of measurement that’s a real pain in the rear.” Bo Nash is 38. He lives in Arlington, Texas, where he’s a technology director for a textbook publisher. He has a wife and ...