Your body needs energy to carry out daily activities. This energy comes from the foods we eat. These foods are measured in units of calories. Energy balance between what is eaten and what is used determines if you will gain or lose bodyweight. If more or less calories are consumed, then weight is gained or lost.
As simple as it may seem, the human metabolism is more complex. Fat, protein, and carbohydrates all have different and distinct nutrient functions in the body. Fat, protein, and carbohydrates are all metabolized differently and are converted into bodyweight with different rates of efficiency.
If more or less calories are consumed, then weight is gained or lost, respectively. Use the following calculator to determine your recommended daily caloric intake.