The Mediterranean diet discouraged soda drinks and the low-fat diet discouraged vegetable oils, nuts, fried snacks, visible fat in meats and soup, fatty fish and tomato sauce.
You can add more if you want later (and are feeling the results), but setting a small habit of a fruit and vegetable will establish an important routine while adding a nutritious source to your daily diet.
Double your vegetable intake and reduce fat -- Both of these changes will significantly decrease the calorie density of your diet without decreasing the volume of food that you consume.