A 'Macro' is short for 'Macronutrient' and macronutrients are made out of fats, protein and carbohydrates these macros are what measure calories.
1 gram protein is 4 calories
1 gram carb is 4 calories
1 gram fat is 9 calories
How do Carbohydrates fuel the body?
There are a different types of carbs simple/refined and complex. Complex carbs such as yams, rice, potatoes, oatmeal etc are ideal for building lean muscle.
Carbs are the muscles tackling fuel! It gives the muscle power. Carbs create an insulin response, which helps transport protein into muscle for building muscle and recovery.
One reason staying hydrated is so important is because when you eat carbs it helps hold water into the muscle this creates muscle glycogen. Muscle glycogen is the extra 'push' in your muscles, when you change to low carb diets you'll often notice lack of energy in your performance also known as having low glycogen levels.
How does Protein fuel the body?
Protein is essential for recovery and building bodily tissue. Protein has a higher metabolic rate it has a thermo gentic response on the body. Muscle needs more food than fat does, that's why protein is extremely important in lower calorie diets because it prevents the breakdown of muscle tissue.
How does Fat fuel the body?
There are different fat sources saturated fats, unsaturated fats and trans fats. Unsaturated fats are benifical for the body. Fat is a source of energy often burned once the glycogen stores in the muscle have been depleted.Fats typically provide more than half of the body's energy needs. Fat from foods broken down into fatty acids, which can travel in the blood and be captured by hungry cells. Fatty acids that aren't needed are packaged in bundles called triglycerides and stored in fats cells which have unlimited storage space.