1.The diet isn't suitable for Mr.Johnson very much.Because he shouldn't have coffee before he go to bed.
2.If he goes on with the diet,maybe he will get bad health in the future,and he may do harm to his stomach or even sleep.
3.Breakfast and Supper are ok for him.There should be no beer for him at lunch.At last,he should drink a glass of milk instead of coffee before he is going to bed,or he could drink coffee in the morning.Eating fruit in the morning is better than in the evening.