Learning how to control portions it is not a very easy task. People usually find it rather hard to estimate what is a serving of their favorite dish, such as a cereal bowl at breakfast or the tuna salad they have at lunch. In this circumstances, losing weight might become not just a challenge, but an impossible task. A perfect plate, for dinner, should be ½ vegetables, ¼ carbohydrates, ¼ proteins (meat, fish, eggs).
What we all should do would be to eat in a coherent, smart way. When you are really hungry you tend to overeat. This leads us to an essential rule in every diet saying that one should never skip a meal. For most of us, the best plan means 3 meals daily and 1 healthy snacking, based on our nutritional needs. Therefore, a person should eat 3 times a day without passing 5 hours between meals. You don’t have to wake up in the middle of the night to eat, but never skip a meal. Also, remember to eat slow, while at the restaurant eat only half the meal and ask to pack the other half. At home use smaller dishes and never go back for seconds. 
When it comes to fruits and vegetables, the ideal thing would be to have 5 servings every day, 3 vegetables, one serving should be raw, and 2 servings of fruits. You can replace one of these 5 servings with a natural juice you have to prepare at home. Most vegetables are poor in fats and calories. Moreover, they fight cancer and cardiovascular diseases. Greens that have a darker color are very rich in nutritive substances. Potatoes are also very nourishing.
The same thing can be applied when talking about fruits. This allows you to eat a wide range of fruits, including those rich in vitamin C, such as citrus and melons. A portion of fruits means 1 medium apple, 1 medium banana, 1/2 cup berries.
Cereals furnish complex carbohydrates and they are a great source of fiber, vitamins and minerals and contain a small amount of fat. You should choose whole-grain bread and cereals. One portion per day means 1 slice of bread, ¼ cup of dry cereals, ½ cup of cooked cereals, rice or cooked pasta. As for meat and eggs, one portion daily means 100 or 120 g meat, 100 to 150 fish or seafood, 2 eggs, or 120 g tofu. Throughout the entire week one should alternate between red meat, white meat, fish, and eggs. You shouldn’t pass over 500 g of meat weekly, of which 1 time should be chicken meat. Don’t exaggerate with fat fish or eggs if you have a high cholesterol.
Dairy products represent a good source of proteins and calcium. If you usually don’t consume dairy products make sure you replace them with foods rich in calcium, such as greens, almonds, berries, or leguminous plants. A portion means 1 cup (125 ml) milk or soy milk, or yogurt, and 50 g cottage cheese. Choose those that are semi-skimmed and natural. 
People who are used to meals poor in fats are much more protected against obesity, heart diseases, cancer, or any other severe health problems. You should have less fats into your diet, especially the animal ones. A balanced diet should not contain more than 20-30% fats of the total calories, which is equivalent with 40-60 fat per day. Saturated fats are solid at room temperature and they increase the risk of different diseases.
The best option would be vegetable fats and oils, such as olive or soy oil. However, these should also be consumed with moderation. One portion means 1 tablespoon oil, butter or margarine, 2 tablespoons salad sauce or mayonnaise.
Everybody knows that sweets are not a diet’s best friends. Therefore, make sure you stay away as much as possible. They are rich in calories and poor in nutritive substances. Avoid them if you want to lose weight and replace them with fruit salads, skimmed milk, berries, or melons. If you still cannot resist to the temptation, choose a good quality chocolate and have a small piece on Sunday. Remember that they are not essential to our body.
As for drinks, only water is totally essential. This is why you should drink at least 1 l every day and more in cases of physical effort. Alcohol, soft drinks and any other drinks containing sugar should be completely eliminated. Alcohol is a no-no when wanting to lose weight as 1 g alcohol means 7 calories, and it has no nourishing substances.