1-He needs to lower his daily calorie intake by the same amount
Calories are used for energy, but will be stored in the body if eaten in excess. If eating less calories than your BMR, you will lose weight. If eating more calories, you will gain weight. If eating at your BMR, you will stay the same weight. Thus, in order to stay the same weight, this person must decrease calories by 2-6% every ten years to compensate for the decreasing BMR if staying at the same level of activity.