Answer:
Calories are a measurement of energy and we are supposed to have a certain number of them a day so we do not gain weight when not wanting to. But if you eat a lot fewer calories then you are supposed to, then you will destroy your body and tons of bad things could happen. However, if you wish to lose some of those extra pounds, then you need to exercise and eat healthy because diet is half or even more then half of your weight and what is happening to it. For portion size, it is how much of each food product you are to consume. Everyone needs a certain grams of fat, carbs, protein and others. So, don't eat too many, especially if they are unhealthy ones, but don't eat to few, you can get very sick.
There is a type of questionnaire called Food frequency questionnaire or FFQ and works to know how many times a patient has eaten an specific food and that is a well known method to obtain information about the patient's diet. This questionaire has a pre-coded data preparation and that requires no nutritional preparation.
The answer is the IntraCellular Fluid (ICF)
