What Are Macros, and Why Do They Matter?
Macronutrients are the three things food is made of in bulk: protein, carbohydrate and fat. Macro tracking means splitting a daily calorie total between them rather than only counting the total. The Macro Calculator does the split.
The three, and what they cost
Protein is 4 calories a gram and is what the body uses to build and repair tissue. It is also the most satiating of the three and costs the most to digest, so a higher-protein diet gives back a little of its own energy.
Carbohydrate is 4 calories a gram and is the body's preferred fuel for hard effort. Working anaerobically runs on it specifically, which is why low-carbohydrate approaches tend to feel worst during high-intensity training.
Fat is 9 calories a gram - more than twice the others - and is needed for hormone production and for absorbing vitamins A, D, E and K. Very low fat intake is not a neutral choice.
Alcohol is a fourth, at 7 calories a gram, contributing nothing structural. It is not a macro anyone tracks on purpose and it does count toward the total.
How a split is built
Start from a daily calorie figure - the TDEE Calculator gives one - then allocate. Protein is usually set first, often around 1.6 to 2.2 grams per kilogram of body weight for someone training, which is where most of the research converges. Fat is usually given a floor of around 0.5 to 0.8 grams per kilogram. Carbohydrate takes whatever calories remain.
That order matters: protein and fat have genuine minimums, carbohydrate is the flexible one.
Which part is worth the attention
Honestly, mostly the protein, and mostly because people under-eat it relative to what the evidence supports for anyone training. The carbohydrate-versus-fat split, at a fixed calorie level and adequate protein, makes far less difference to body composition than the internet suggests. Studies that match calories and protein find small differences between high-carb and high-fat approaches.
So the practical hierarchy is: total calories first, protein second, the rest third. Tracking all three to the gram is a lot of effort for the smallest part of the effect, and for many people it is more effort than it is worth. If tracking food is something that has caused you difficulty in the past, that is a good reason to use a figure as background context rather than a daily target, and to talk to a dietitian rather than a calculator.
Common questions
Do I need to hit my macros exactly?
No. Within ten per cent is closer than the underlying estimates are accurate.
Is a gram of protein in chicken the same as in a shake?
For the calorie arithmetic, yes. Whole foods bring fibre and micronutrients that a shake does not, so they are not equivalent in every sense.
What about fibre?
It is a carbohydrate, largely not absorbed for energy, and worth attention in its own right. Most people get well under the recommended 30 grams a day.
Does meal timing matter?
Far less than the daily totals. It matters at the margins for athletes training twice a day.
Want a split from your own calorie figure?