The big three
Macronutrients are the nutrients your body needs in large amounts, and the ones that carry calories:
- Protein (4 kcal/g) — the building material: muscle, organs, enzymes, skin. The macro that protects muscle in a deficit and builds it in a surplus.
- Carbohydrates (4 kcal/g) — the preferred fuel, especially for hard training and your brain. Includes fiber, the part that feeds your gut instead of your bloodstream.
- Fat (9 kcal/g) — the densest fuel, and structurally essential: hormones, cell membranes, and the absorption of several vitamins depend on it.
Alcohol technically carries calories too (7 kcal/g) — worth logging, not worth building a plan around.
Calories first, macros second
Total calories decide whether your weight moves; macros decide what the change is made of and how the process feels. Enough protein means a deficit costs fat rather than muscle; sensible carbs mean training doesn't fall apart; a fat minimum keeps hormones in business. Same calories, different splits, meaningfully different outcomes.
What the app does with this
Your plan works in exactly that order: calories from your goal and expenditure, then a macro split with protein set first from your lean mass and fat kept above a floor. The following articles take each macro one at a time.