Macros Explained
Macronutrients — protein, carbohydrates, and fat — are the three major nutrient categories that provide calories. Protein and carbohydrates provide 4 calories per gram; fat provides 9 calories per gram. Alcohol provides 7 calories per gram and is not a macronutrient but contributes to calorie intake.
Protein
The RDA for protein is 0.8g per kilogram of body weight (0.36g/lb) — the minimum to prevent deficiency. For active adults, research supports 1.6–2.2g/kg for muscle building and 1.2–1.6g/kg for maintenance. Protein has the highest thermic effect (25–30% of calories burned in digestion) and the highest satiety of any macronutrient.
Carbohydrates
Carbohydrates are the body's preferred fuel source, particularly for high-intensity exercise and brain function. The Dietary Guidelines for Americans recommend 45–65% of calories from carbohydrates. High-fiber carbohydrates (vegetables, legumes, whole grains) improve satiety and gut health; refined carbohydrates spike blood sugar and contribute to fat storage.
Fat
Dietary fat is essential for hormone production, fat-soluble vitamin absorption (A, D, E, K), and cell membrane integrity. Healthy fats (monounsaturated, polyunsaturated, omega-3) support cardiovascular health. The Dietary Guidelines recommend 20–35% of calories from fat, with saturated fat under 10%.