Not all calories are equal. The "Calorie is a Calorie" tautology is wrong! Surprisingly! - Processed foods make us gain weight much faster than the same equal calories of natural foods.
The nutrients we eat and drink and the calories they carry cannot vanish, but they can be redirected to other non-energy, "non-countable." purposes.
- The portion of food dedicated to tissue regeneration varies depending on the body's requirements and diet quality and quantity. The rest is converted into energy and fat and influences body weight. Surprisingly! - Processed foods make us gain weight much faster than the same equal calories of natural foods. Not all calories are equal.
- When you refuel your car, you know how much energy you will get (driving range). When a person eats and drinks, some food (by analogy) enters the oil tank and is intended for maintenance - but the proportions change!
Since the routing of food between the two primary uses (tissue building and maintenance, as opposed to available energy and fat accumulation) is not fixed and differs from person to person, it is inaccurate to sum the calories in food and beverages.