When people exercise, they often don’t lose as much weight as scientists expect. To find out why, researchers randomly assigned 171 sedentary overweight or obese people to burn: ■ A: no extra calories, ■ B: roughly 100 extra calories a day, or ■ C: roughly 250 extra calories a day. All exercise sessions were monitored. After six months, group A had lost ½ pound, group B had lost about 1 pound, and group C had lost 3½ pounds. Based on how much the groups exercised, the researchers calculated that group B should have lost another 3 pounds and group C should have lost another 6 pounds. What happened? The people in groups B and C “compensated” for the exercise by eating roughly 100 extra calories a day.