Growth depends on caloric intake and macro-nutrients that the calories come from. Basically, food is measured in calories (kcal) because it is used as fuel for all body functions by breaking down and releasing heat. Calories are simply defined as the amount of energy required to raise the temperature of 1 gram of water by 1 degree Celsius.

When considering the value of calories, there are several variables that need to be remembered. For example, the quality of food will affect nutrient absorption and utilization efficiency, and if there is a limited number of calories consumed, your body may actually end up sacrificing protein for fuel.