Macronutrients are the three main nutrient categories the body needs in large amounts to produce energy and build tissue.

The three macronutrients:

• Carbohydrates — 4 calories per gram. Primary energy source.
• Protein — 4 calories per gram. Builds and repairs tissue.
• Fat — 9 calories per gram. Energy storage, hormones, cell membranes.

Calorie density matters: Fat has more than twice the calories per gram of carbs or protein — critical for weight management.

Typical recommended ratios:

• Carbs: 45–65% of total calories
• Protein: 10–35%
• Fat: 20–35%

These ratios shift dramatically based on goals (keto, athletic performance, weight loss).

Reference:

Wikipedia: Macronutrient

https://en.wikipedia.org/wiki/Macronutrient