A macro or macronutrients are nutrients that your body requires in large quantities such as protein, carbs, fat, water and fibre. The Protein provides 4 calories per gram, Carbs provides 4 calories per gram, Fat provides 9 calories per gram, Water and Fibre do not provide any energy. The macro calculator help you determine your daily targets for three goals: Weight Loss, Weight Gain and Maintain Weight. A good balance of these macronutrients is essential to reach your fitness goals.