Protein, carbohydrates, and fat — the three nutrients that provide calories. Protein and carbs deliver 4 kcal per gram; fat delivers 9 kcal per gram.

Protein is the most satiating macronutrient, has the highest thermic effect (20–30% of calories burned during digestion), and is essential for preserving muscle while in a calorie deficit.

Apps like MyFitnessPal, Cronometer, or MacroFactor let you log food and see your protein, carb, and fat totals. Hitting within 10g of each target is good enough for most goals.

Yes. The default split (roughly 30% protein, 40% carbs, 30% fat) suits most goals. Low-carb or ketogenic diets shift carbs to fats. High-carb endurance athletes may increase carbs to 55–60% and reduce fat.