How does the body use carbohydrates, fats and proteins?
Carbohydrates and fats are primarily energy sources. Proteins are used in the growth of muscle tissue.
Vitamins are necessary as well for the protein reconstruction to be effective, as well as some digestive functions.
The necessity of obtaining sufficient amounts and types of protein in a diet is one of the major considerations (drawbacks?) in pursuing a Vegan diet. Meats also contain fats, so a healthy diet does need to consider the balance of energy sources.
Two important rules should be observed for healthy diets:
1. TOO MUCH of ANYTHING is bad for you.
2. You CANNOT gain more weight (mass) than you ingest.
Whatever your taste preferences, the fact is that most dietary "problems" involve excessive eating more than the dietary mix (although that is also often skewed in the process).