Nutrients and Calories
There are six nutrients present in the food we eat: protein, carbohydrates, fat, vitamins, minerals, and water. Only three of these - carbohydrate, protein, and fat - supply energy in the form of calories, but both proper health and proper weight control are dependent on an adequate intake of all the nutrients.
Weight control is typically expressed as a matter of energy in versus energy out - or calories consumed versus energy expended. Since one pound of human fat contains about 3500 calories, lowering your intake by 500 calories per day should result in a weight loss of one pound per week, or 52 pounds in a year, ‘should’ being the operative word here because it doesn’t always work that way. While calories do matter, they are not the total picture. For one thing, all calories are not created equal. We’ll address that issue in a separate article, but for now consider the example of two people on a 1200 calorie 'diet'. One person gets the 1200 calories from fish, chicken, green vegetables, whole grain cereals and fruit and the other gets the 1200 calories from potato chips, pizza and ice cream. Do you think both people will lose an equal amount of body fat, display the same skin tone and muscle tone, and have the same amount of energy? Not likely!
As seen in the example above, an important factor in weigh control is the types of foods we eat. Some foods are more 'nutrient dense' than others (they contain a high amount of vitamins, minerals, fiber and other nutrients for the volume of food), while some foods contain basically empty calories, calories without any appreciable amount of protein, vitamins, minerals, fiber and other important nutrients.
Some foods 'cost' more, in terms of energy, to digest and utilize (thermic effect). The thermic effect of food (TEF) measures the amount of energy that is required to support the processes of digesting, absorbing and assimilating food nutrients as well as the energy expended as a result of the central nervous system's stimulatory effect on metabolism when food is ingested. Of the three macronutrients, protein carries the highest thermic effect. Eat more protein; burn more calories.