Act as my coach for calculating my macros, not a generic macro calculator. Before giving me anything, ask me for: my height, current weight, a rough body-fat estimate (or an honest description if I do not know it), my goal (fat loss, muscle gain, or recomposition), my activity level, and how many days a week I train.
Once you have that:
1. Work out my lean body mass from my weight and body-fat estimate. Show me this number and use it, not my total weight, as the basis for protein.
2. Set my daily protein target from my lean mass, matched to my activity level and goal, and explain your reasoning in plain words.
3. Set a sensible daily fat target for my size and sex. Do not set it very low without a specific reason tied to my goal.
4. Give me the remaining calories as carbohydrate, based on my goal (a deficit for fat loss, maintenance for recomposition, a modest surplus for muscle gain). Do not treat carbs as the macro to cut first.
5. Only count complete proteins towards my protein target: meat, fish, eggs, dairy, whey, EAA. Bread, rice, oats and legumes are carbs, not protein, even though they contain some.
6. Show me the maths at each step, not just the final numbers, so I understand where they came from.
7. Tell me these numbers are a starting point, not a permanent fact, and should be recalculated as my weight and body fat change.
Ask me the setup questions now, before giving me any numbers.
Why this prompt works
Most online macro calculators use total bodyweight and a generic activity multiplier, which quietly overstates protein for anyone carrying meaningful body fat. Lean body mass is the better basis because muscle tissue is what actually uses dietary protein and fat mass mostly does not, so two people at the same scale weight but different body-fat percentages need genuinely different protein targets, not the same one.
Carbohydrate is calculated last and treated as the flexible macro that fills the remaining calories, never the first one cut. That ordering, protein and fat set from real targets first and carbs filling the rest, is what separates an actual macro calculation from a diet app's default split applied to everyone regardless of goal or body composition.
A real-world example
Take two people at the same 80kg bodyweight: one at 15% body fat, one at 30%. Their lean mass differs by roughly 12kg, which is a meaningful difference in the protein target this prompt would set for each of them, even though a generic calculator using total bodyweight would hand them the identical number.
That gap is exactly why a calculation based on lean mass matters more than which macro app someone happens to open.
Where a single prompt hits its ceiling
These numbers are a snapshot. The moment your weight or body fat changes, and both change continuously through a fat loss or muscle gain phase, the calculation is out of date, but a one-off prompt has no way to know that unless you notice and recalculate yourself.
It also cannot check that your body-fat estimate is accurate. Macro calculations are only as good as the inputs, and a self-estimated body-fat percentage that is off by five or ten points changes the lean mass figure enough to shift every number that follows from it.
