Step 2 - The Nutrients
Where do the calories come
from?
There are six classes of nutrients - carbohydrates, fats, proteins, vitamins, minerals, and water.
Only the first three are energy producing, and an important thing to remember about these three is that there are twice as many calories/gram in fats as there are in either carbohydrates or protein.
Also important is an adequate supply of fiber, which can be found in fruits, vegetables, and whole grains. Fiber is not digested and therefore is calorie-free.
Read about where the calories go in Step 3

