Macronutrientscarbohydrates

Macronutrients are the nutrients required by the human body in larger amounts to supply energy and to support growth, tissue maintenance, and metabolic functions. They include carbohydrates, proteins, and fats. Water is essential but is not classified as a macronutrient in the same sense.

Carbohydrates provide 4 kilocalories per gram and serve as the body’s main energy source, especially for brain and high‑intensity activity. They range from simple sugars to complex starches and dietary fiber. Guidelines favor complex carbohydrates from fruits, vegetables, whole grains, and legumes and limit added sugars and refined grains.

Proteins supply 4 kilocalories per gram and provide amino acids for tissue repair, immune function, and enzymes and hormones. There are 20 standard amino acids, nine of which are essential. Daily protein needs are about 0.8 g/kg for adults, higher for athletes. Sources include meat, dairy, fish, legumes, and some grains and seeds; combining foods can provide all essential amino acids.

Fats provide 9 kilocalories per gram and are a dense energy source, essential for cell membranes, vitamin absorption, and hormone production. They supply essential fatty acids such as linoleic and alpha-linolenic acid. Fats are categorized by saturation and chain type; emphasis on unsaturated fats from fish, nuts, seeds, and vegetable oils, with limits on saturated fats and avoidance of trans fats. General guidance is 20–35% of calories from fat.

Total energy intake should align with expenditure to maintain, lose, or gain weight. Macronutrient distribution should be tailored to health goals, activity level, and dietary preferences, but a balanced approach emphasizes whole foods, variety, and moderation.