At least 5 different portions a day is the fruit and vegetable target - approx. 80g is one serving.
Calories in vegetables are generally quite low. Exceptions are potatoes and related root vegetables - 'starchy' foods.
Potatoes don't count towards your 5 A DAY but should form the carbohydrate part of your meal. Vegetables should make up half of your plate. As calories in vegetables are so low, they are dieters friend!