Energy and Diet: How The Body Turns Food Into Fuel The three main nutrients used for energy are carbohydrates, protein, and fats, with carbohydrates being the most important source. Your body can also use protein and fats for energy when carbs have been depleted.Click to see full answer. Simply so, which nutrient provides the most energy?Even though fats are the most energy-dense of the three energy-yielding nutrients, carbohydrates, which provide four Calories/gram are your body’s first choice for energy, especially immediate energy.Beside above, what food group is the best source of energy? Carbohydrates. Carbohydrates are the body’s main source of energy. The fruit, vegetables, dairy, and grain food groups all contain carbohydrates. In this regard, which gives more energy protein or carbs? Because proteins are complex molecules, the body takes longer to break them down. As a result, they are a much slower and longer-lasting source of energy than carbohydrates.What nutrient can directly supply energy?The food you eat supplies many types of macronutrients — carbohydrates, fats and proteins — which deliver the energy (or calories) your body needs to function. Food also supplies micronutrients, such as vitamins and minerals, which don’t provide calories but help the body with chemical reactions.