The Centers for Disease Control and Prevention says physical activity is increasing among U.S. adults. At least that’s what U.S. adults say they are doing. It’s almost as hard to get good information about activity as it is to get information about diet. The latest results could be true. They are consistent with some studies, but not others. If so, it’s good news but doesn’t this mean that weight gain must be due to overeating, not to too little activity (at least across the population)?