Macronutrients, usually shortened to macros, are the three nutrients that provide energy. Protein, carbohydrates, and fat. Every calorie in every food you eat comes from one of these three sources, plus alcohol if applicable. Tracking macros means tracking the grams of each rather than just total calories.
The full picture
Protein provides 4 calories per gram and supplies the amino acids your body uses for muscle repair, enzyme production, and immune function. It is the only macro with a clear dose-response for body composition. Hitting 1.6 to 2.2 grams per kilogram of bodyweight per day reliably outperforms lower intakes for muscle retention during cuts and muscle gain during bulks.
Carbohydrates also provide 4 calories per gram. They are the preferred fuel for high-intensity exercise because they convert to glycogen and ATP fastest. Carb needs scale with training volume, not with morality. A powerlifter doing two-hour sessions needs 4 to 6 g per kg per day. A sedentary office worker can thrive on less than 2 g per kg per day.
Fat provides 9 calories per gram, more than double the others, because fat molecules are denser and more reduced. It supports hormone production, vitamin absorption, and cell membrane integrity. Aim for at least 0.5 to 0.8 g per kg per day for health, then fill remaining calories with whatever carb-to-fat ratio you prefer.
How macros are calculated
Standard approach. Set protein at 1.6 to 2.2 g per kg bodyweight. Set fat at 0.6 to 1.0 g per kg. Fill the remaining calories with carbs. Example: 80 kg lifter at 2400 calories. Protein 160 g = 640 cal. Fat 70 g = 630 cal. Remaining 1130 cal ÷ 4 = 283 g carbs. Adjust the carb-to-fat ratio based on preference and training volume.
Common misconceptions
- "Clean" vs "dirty" macros do not exist for body composition. A gram of carbs from rice and a gram from candy have identical metabolic effects. Whole foods win on micronutrients, satiety, and fiber, not macros.
- You do not need a high-protein meal every 3 hours. Total daily protein matters far more than distribution, although 3 to 5 doses of 0.4 to 0.55 g per kg per meal optimize muscle protein synthesis.
- Cutting carbs does not directly burn fat. Lower carbs depletes glycogen and water, which is why the scale drops fast in the first week. Body fat only changes when calories are below TDEE.
Citations
- Helms ER, Aragon AA, Fitschen PJ. (2014). Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. JISSN, 11(20).
- Aragon AA, Schoenfeld BJ. (2013). Nutrient timing revisited. JISSN, 10(1), 5.
- Morton RW et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation. BJSM, 52, 376-384.