Carbohydrates are one of the most important sources of energy for the body of many organisms, including humans. They provide about 4 kcal per gram. Fat is also one of the three main macronutrients, along with carbohydrate and protein. Compared to carbohydrate and protein, each gram of fat provides 9 kcal per gram.
Hence, the two energy-providing nutrients are carbohydates and fats.