Macro basics
What are macros, in plain English?
Macros are the three nutrients your body needs in large amounts. Counting them is just splitting your calorie target into three parts, and one of them matters more than the other two.
The three, and what they cost
| Macro | Calories per gram | What it mainly does |
|---|---|---|
| Protein | 4 | Builds and repairs tissue; keeps you full |
| Carbohydrate | 4 | Fuels the brain and hard exercise |
| Fat | 9 | Hormones, cell membranes, fat-soluble vitamins |
Alcohol supplies 7 calories per gram and is sometimes called a fourth macro. It is not required by the body and is usually left out of a split.
That table is the whole idea: calories tell you how much energy you ate, macros tell you where it came from.
Why bother splitting them at all
Two 2,000-calorie days can produce different outcomes. In controlled trials, higher-protein diets preserved more lean mass during weight loss than lower-protein diets at the same calorie intake.[1] Protein also has the largest thermic effect of the three — a larger share of its calories is spent digesting it — and is the most satiating per calorie.
That is the practical case for macros. Not that carbohydrate or fat are bad, but that the protein share changes what you lose or keep while the calorie total decides the direction.
Setting your own split
Set protein and fat as floors, then let carbohydrate fill whatever is left. That way the two nutrients with real minimums are protected and the flexible one absorbs the variation.
- Protein: 1.6–2.2 g per kg of body weight if you train or are eating in a deficit; 1.2–1.6 g/kg otherwise.[1]
- Fat: at least 0.6 g per kg, or roughly 20–35 per cent of calories, which is the accepted distribution range for adults.[2]
- Carbohydrate: everything remaining.
At 2,000 calories and 70 kg: 140 g protein (560 cal) and 65 g fat (585 cal) leaves 855 calories, or about 214 g of carbohydrate.
Three worked splits at the same body weight
The same 70 kg person, three goals. Only the calorie total and the protein floor really move; carbohydrate absorbs the difference, which is the point of setting it last.
| Goal | Calories | Protein | Fat | Carbohydrate |
|---|---|---|---|---|
| Fat loss | 1,700 | 154 g (2.2 g/kg) | 57 g (30%) | 149 g |
| Maintenance | 2,100 | 126 g (1.8 g/kg) | 70 g (30%) | 241 g |
| Muscle gain | 2,400 | 126 g (1.8 g/kg) | 73 g (27%) | 316 g |
Notice what does not change much: protein in grams is nearly flat across maintenance and gaining, and rises for fat loss rather than falling. That is the single most common thing people get backwards. Cutting calories is when protein matters most, because it is the nutrient standing between a deficit and lost muscle.
Fat stays inside the 20–35 per cent band in all three. Carbohydrate ranges from 149 g to 316 g — more than double — without anything being wrong in either case.
Four mistakes that make the numbers useless
- Setting carbohydrate first. A percentage split assigned to all three at once means every change to one silently changes the others. Floors for protein and fat, remainder for carbohydrate, is more robust.
- Lowering protein while cutting. Protein calories look expensive when the total is small. They are the ones worth keeping.
- Weighing cooked food against raw entries. A hundred grams of raw chicken and a hundred grams of cooked chicken are not the same food. Pick one convention and stay with it.
- Tracking on weekdays only. Two untracked days can undo a five-day deficit by themselves, and they are the days most likely to be eaten out.
None of these are precision problems. They are consistency problems, which is the category almost every failed attempt at tracking actually falls into.
Counting without weighing every meal
Precision is not the point; consistency is. Three approaches, in order of effort:
- Track a normal week once. Most people eat a small rotation of meals. Learn what those cost and you can estimate the rest.
- Anchor the protein. If you hit your protein floor and your calorie total, the split largely takes care of itself.
- Use published numbers where they exist. Packaged food and chain restaurants publish theirs, which removes the guesswork from the meals hardest to estimate by eye.
What macros will not tell you
A split says nothing about fiber, sodium, micronutrients, or how a food was made. Two identical macro days can differ a great deal in how well they feed you. Macros are a budget, not a definition of a good diet — which is why the meal data on this site shows fiber and sodium beside calories and protein rather than stopping at the three.
Educational information, not individualized medical advice.
Frequently asked questions
Do I have to hit my macros exactly?
No. Within about 5 grams of protein and fat, and within roughly 50 calories of the total, is close enough for the result to be indistinguishable over a week.
Is counting macros better than counting calories?
For weight change, the calorie total is what decides direction. Macros mostly decide what you keep while it happens, and how full you feel getting there.
What is IIFYM?
“If it fits your macros” — the idea that food choice is unconstrained as long as the day's totals land. It works arithmetically and ignores fiber, sodium and micronutrients, so it is a starting framework rather than a finished plan.
Keep reading: Free macro calculator · Calories vs macros · Calculate macros by hand · What protein actually does