Americans are still gaining weight though reducing the fat intake because______.

A．He shouldn't eat any sugar.
B．He should only eat nonfat food.
C．He shouldn't eat any food.
D．He shouldn't eat too much.

A．people increase the number of calories they eat per day and gain weight
B．the "low fat" yogurt group ate less calories later than the other group
C．two groups ate the same amount of yogurt
D．people who eat low fat yogurt will not gain weight