Macros — short for macronutrients — are the three nutrients your body needs in large amounts: protein, carbohydrates and fat. Everything you eat is built from them, and each supplies energy: protein and carbs provide 4 calories per gram, fat provides 9. When people "count macros", they're tracking those three numbers instead of calories alone.
If you've ever wondered why two 500-calorie meals can leave you feeling completely different — one satisfied for hours, one hungry by 3pm — macros are the answer. Calories measure how much energy you eat. Macros describe what that energy is made of, and that turns out to matter enormously for hunger, muscle and how sustainable your diet feels.
The three macros at a glance
| Macro | Calories per gram | Main jobs | Found in |
|---|---|---|---|
| Protein | 4 | Builds and preserves muscle; keeps you full; repairs tissue | Chicken, fish, eggs, Greek yogurt, beans, lentils, tofu |
| Carbohydrates | 4 | Primary energy source, especially for your brain and training | Bread, rice, oats, potatoes, fruit, vegetables |
| Fat | 9 | Hormones, brain function, absorbing vitamins A, D, E and K | Olive oil, nuts, avocado, oily fish, dairy, eggs |
(There's technically a fourth calorie source — alcohol, at 7 per gram — but your body has no use for it, which is why it's not a macronutrient. It still counts toward your day, unfortunately.)
Protein: the one to get right first
Protein does two things no other macro can. It gives your body the raw material to keep your muscle while you lose fat — without enough of it, a chunk of every kilo you lose is muscle, which is exactly what you don't want. And it's the most filling macro by far, which makes a calorie deficit dramatically easier to live with.
Most beginners eat far less than they need. For weight loss, the sports-nutrition research consistently supports around 1.2–1.6 grams per kilogram of body weight per day — well above the basic health minimum of 0.8 g/kg:
| Your weight | Daily protein target (weight loss) |
|---|---|
| 70 kg (154 lb / 11 st) | 84–112 g |
| 85 kg (187 lb / 13 st 5) | 102–136 g |
| 100 kg (220 lb / 15 st 10) | 120–160 g |
For context, a chicken breast has roughly 30 g, three eggs about 18 g, a tin of tuna about 25 g. Hitting 100+ grams takes a little intention — it doesn't happen by accident. Get your exact number from the protein calculator.
Carbohydrates: not the enemy, just the flexible one
Twenty years of diet culture blamed fat; the last ten blamed carbs. The evidence supports neither. Carbs don't make you gain weight — excess calories do. Carbohydrates are your body's preferred fuel, especially for your brain and for any kind of training, and diets that ban them work only because banning a whole macro quietly cuts calories.
Treat carbs as your flexible macro: once protein and fat are set, carbs fill whatever calories remain. Prioritise ones that bring fibre with them — oats, potatoes, beans, fruit, wholegrain bread — because fibre is doing quiet, unglamorous work for your fullness and your health the whole time.
Fat: essential, just expensive
Fat is not optional. Your hormones — including the ones that regulate appetite — are built from it, and several vitamins can't be absorbed without it. Very-low-fat diets feel terrible for a reason.
The catch is arithmetic: at 9 calories per gram, fat costs more than twice what protein and carbs do. A tablespoon of olive oil is ~120 kcal; the same calories buy you 300 g of strawberries. Neither is "bad" — fat is just the macro to measure rather than pour. A sensible weight-loss range is roughly 20–35% of your daily calories.
How many of each should you eat?
There's no universal ratio — anyone selling you "the perfect macro split" is skipping the only step that matters: your own numbers. The reliable order of operations is:
- Find your calorie target. Your TDEE minus 300–500 kcal. Say that's 1,800.
- Set protein by body weight. 80 kg (176 lb / 12 st 8) → about 120 g → 480 kcal.
- Set fat at 25% of calories. 1,800 × 0.25 = 450 kcal → 50 g.
- Carbs get the rest. 1,800 − 480 − 450 = 870 kcal → about 215 g.
That's it — that's the whole "macro diet" the fitness industry wraps in mystery. The macro calculator does these four steps for you in ten seconds, in kg, lb or stone.
Do you actually have to count them?
Honestly? Not forever — and maybe not precisely at all. Counting macros for even two or three weeks is like using a sat-nav in a new city: after a while you know the routes. You'll learn what 30 g of protein looks like on a plate and roughly what your usual meals contain, and many people then coast on that knowledge for good.
A gentler starting version that captures most of the benefit: hit your protein number, stay near your calories, and let carbs and fat land where they fall. Two numbers, not four. When you're ready for the full method, read how to count macros — or get the whole system, with food lists and four weeks of structure, in Macro Mastery ($9.99).
FAQ
What does "macros" actually stand for?
Macronutrients — the nutrients needed in large (macro) amounts: protein, carbohydrates and fat. Vitamins and minerals are micronutrients, needed in tiny amounts.
Are calories or macros more important for weight loss?
Calories determine whether you lose weight; macros determine how it feels and what you lose. A calorie deficit with good macros loses fat while keeping muscle and hunger manageable. The same deficit with poor macros loses more muscle and feels far harder.
What is a good macro ratio for weight loss?
Ranges beat ratios, but a common effective pattern is protein set by body weight (1.2–1.6 g/kg), fat at 20–35% of calories, carbs filling the remainder. Two people with different bodies should not eat the same ratio — calculate your own.
Is a high-protein diet safe?
For healthy people, intakes well above the RDA show no evidence of harm in the research — the "protein damages kidneys" claim traces back to studies of people with existing kidney disease. If you have kidney problems, talk to your doctor before increasing protein.
Do vegetables have macros?
Everything with calories has macros. Vegetables are mostly carbohydrate (with some protein), but so few calories per plateful that most counters treat non-starchy veg as close to free. Eat them liberally.
What are macros on a food label?
Look for protein, carbohydrate and fat per serving — those three lines are the macros. US labels list them per serving; UK labels usually show per 100 g, which makes comparing products easier.
Written by Ricky Valentine · Last updated 31 August 2026
Citations to verify in edit pass: protein intake range (Helms/Phillips-style systematic reviews, or the ISSN position stand on protein); RDA 0.8 g/kg (NIH/ODS or UK SACN); protein-and-kidney evidence review; fat 20–35% (US Dietary Guidelines AMDR); NHS Eatwell Guide for the UK framing.