Macros 101
6 min read
“Tracking macros” sounds technical, but the idea is simple: your calories come from three nutrients, and getting the balance roughly right supports training, recovery, appetite control, and — in a diet — keeping the weight you lose mostly fat rather than muscle.
The three macronutrients
Protein — 4 calories per gram. Supplies amino acids to build and repair muscle, skin, enzymes, antibodies, and hormones. In a calorie deficit, adequate protein is the single biggest factor determining whether the weight you lose is fat or lean tissue. It is also the most satiating macro per calorie, so a higher-protein diet tends to control hunger better.
Carbohydrate — 4 calories per gram. Your body’s preferred fuel for moderate-to-hard exercise, stored as glycogen in muscle and the liver. Carbs are not “essential” in the strict biochemical sense (the body can make glucose from protein and fat), but they are very useful for training performance, and for most people they make eating enjoyable and sustainable.
Fat — 9 calories per gram. Required for hormone production (including sex hormones), cell-membrane structure, nerve function, and the absorption of the fat-soluble vitamins A, D, E, and K. Because fat is more than twice as energy-dense as protein or carbs, small changes in fat intake move your calorie total a lot.
How much protein
For active people and anyone in a calorie deficit, the evidence points to roughly 1.6 to 2.2 grams of protein per kilogram of body weight per day.
| Body weight | Protein target (1.6–2.2 g/kg) |
|---|---|
| 55 kg (121 lb) | 88 – 121 g |
| 70 kg (154 lb) | 112 – 154 g |
| 85 kg (187 lb) | 136 – 187 g |
| 100 kg (220 lb) | 160 – 220 g |
Spreading it across three or four meals of 25–45 g is slightly better for muscle protein synthesis than one huge serving. If you are very overweight, base the target on a weight closer to your goal weight or on lean mass, so the number stays reasonable.
Setting carbs and fat
Once protein is fixed and your total calorie target is set (from the calorie calculator), carbs and fat split whatever calories remain. This split is largely a matter of preference and training style:
- Balanced — roughly 40% carbs / 30% fat / 30% protein. A sensible default that works for most people and most training.
- Higher carb (45–55%). Helpful if you do a lot of high-intensity intervals, team sports, or endurance work, where glycogen matters.
- Lower carb (under ~25%) or keto. Some people find it blunts appetite well and prefer the food choices. It is not required for fat loss — that is driven by total calories — and it can reduce top-end sprint and heavy-lifting performance for some.
Keep fat above about 0.5 g/kg of body weight so hormone function is not compromised, even on a higher-carb plan.
Worked example
A 75 kg person eating 2,200 calories to lose fat slowly:
- Protein: 165 g (2.2 g/kg) = 660 calories
- Fat at 30% of total: 733 calories = ~81 g
- Carbs get the rest: 2,200 − 660 − 733 = 807 calories = ~202 g
The macro calculator does this arithmetic for any calorie target and split.
A sample day at 2,200 calories (165 P / 200 C / 80 F)
| Meal | Rough contents | P / C / F (g) |
|---|---|---|
| Breakfast | 3 eggs + 40 g oats + a banana + coffee | 25 / 55 / 20 |
| Lunch | 150 g chicken breast, 200 g cooked rice, big salad, 1 tbsp olive oil | 45 / 60 / 16 |
| Snack | 200 g Greek yoghurt + berries + honey | 20 / 25 / 4 |
| Dinner | 170 g salmon, 300 g potatoes, roasted vegetables | 40 / 45 / 22 |
| Evening | 30 g whey in milk + an apple | 30 / 25 / 6 |
| Total (~) | 160 / 210 / 68 |
Close enough — within ~10 g on each. Notice the protein is anchored by a lean source at every meal, and the fat is mostly from whole foods (eggs, oil, oily fish) rather than added sauces.
Fibre and micronutrients still matter
Macros are the frame, not the whole picture:
- Fibre — aim for roughly 14 g per 1,000 calories (so ~30 g on this plan). It aids fullness, digestion, and blood-sugar control. It comes “free” if your carbs are mostly vegetables, fruit, legumes, and whole grains.
- Micronutrients — a diet that hits its macros from mostly whole foods, with plenty of colour on the plate, usually covers vitamins and minerals. Common gaps on a cut: vitamin D, iron (especially menstruating women), omega-3s, and calcium if dairy is low.
- Water and electrolytes scale with a higher-protein, higher-fibre diet — see how much water should you drink.
You do not need to track fibre or micros gram by gram; building meals around lean protein, vegetables, fruit, and whole grains handles it.
How precise do the numbers need to be?
Not very. Aim to land within about 10 g of each macro target and within roughly 100 calories overall, most days. Weekly consistency beats daily precision — a day that runs 20 g high on carbs and low on fat is not a problem if the week averages out.
Whole foods make the targets easy to hit without weighing everything forever: lean meat, fish, eggs, Greek yoghurt, legumes, tofu for protein; vegetables, fruit, potatoes, rice, oats for carbs; nuts, olive oil, avocado, oily fish for fat.
Common mistakes
- Under-eating protein while dieting, then wondering why strength dropped and the scale weight came back as fat.
- Fearing carbs. They are not uniquely fattening; excess total calories are.
- Cutting fat too low to make the carbs “fit,” which can affect hormones, mood, and vitamin absorption.
- Weighing food cooked one day and raw the next — pick one and be consistent (raw weights are more reliable).
The bottom line
Set protein first at 1.6–2.2 g/kg, keep fat at or above 0.5 g/kg, and let carbs fill the rest of your calorie target based on how you train and eat best. Total calories decide weight change; the macro split decides how you feel, perform, and hold on to muscle. Get grams for your target with the macro calculator, and if you do not have a calorie target yet, start with the calorie calculator.