macronutrients

Macronutrients are nutrients required in relatively large amounts by the human body to provide energy, support growth, and maintain function. The term typically includes carbohydrates, proteins, and fats; water is often discussed alongside macronutrients because it is needed in large quantities for hydration and metabolic processes. Each macronutrient contributes energy: carbohydrates about 4 kcal per gram, proteins about 4 kcal/g, and fats about 9 kcal/g.

Carbohydrates supply the body’s primary energy source and include sugars, starches, and dietary fiber. Digested carbohydrates yield glucose for immediate use or storage as glycogen; fiber, while not fully digested, supports gut health and satiety.

Proteins provide amino acids for tissue maintenance, immune function, and the synthesis of enzymes and hormones. Nine amino acids are essential in the diet because the body cannot synthesize them in sufficient amounts.

Fats provide concentrated energy and are necessary for the absorption of fat-soluble vitamins and the function of cell membranes. They supply essential fatty acids, such as linoleic acid and alpha-linolenic acid, which the body cannot produce.

Dietary guidelines often express macronutrient needs as proportions of total energy, known as the Acceptable Macronutrient Distribution Ranges (AMDR). Common ranges are carbohydrates 45-65%, fats 20-35%, protein 10-35%, with adjustments for age, activity, health status, and goals. Food choices within each group, emphasizing nutrient-dense sources, influence overall health.