Protein, carbs and fat: how to count macros

To count macros, you track how many grams of protein, carbs and fat you eat, and turn them into calories using a simple rule: protein and carbs give 4 kcal per gram, fat gives 9 kcal per gram. Set a daily calorie target, decide what share goes to each of the three, then work out the grams. That is the whole thing. The rest is just tracking as you go.

Here is how it works in plain terms.

What macros actually are

"Macros" is short for macronutrients: the three things in food that carry calories. Protein, carbohydrate and fat. Alcohol technically has calories too, but it is not a macro you build meals around.

Each one does a different job:

• Protein builds and repairs muscle and keeps you feeling full. Meat, fish, eggs, dairy, beans, tofu.
• Carbs are your body's main quick fuel. Bread, rice, pasta, potatoes, oats, fruit.
• Fat supports hormones and helps you absorb some vitamins. Oils, butter, nuts, cheese, oily fish.

Counting macros just means keeping an eye on how much of each you eat, rather than only watching total calories.

The 4/4/9 rule

This is the bit that ties grams to calories. Every gram of a macro carries a fixed amount of energy:

So 30g of protein is 120 kcal. A 40g portion of carbs is 160 kcal. A 20g dollop of fat is 180 kcal. Fat is the dense one, more than double the calories of the other two per gram, which is why a splash of oil adds up faster than it looks.

Add the three together and you get the total calories of a meal. This is exactly how a food label is put together, so once you know the rule you can sense-check any packet in your kitchen.

How to split your calorie target

Start with your daily calorie target. If you have not got one yet, work it out first (our calorie guide walks through the BMR and TDEE maths). Then decide what percentage of those calories goes to each macro.

A balanced starting split that suits most people is:

• Protein: 30%
• Carbs: 40%
• Fat: 30%

Let's split a 2,000 kcal day using it.

Protein. 30% of 2,000 is 600 kcal. Protein is 4 kcal per gram, so 600 divided by 4 is 150g.

Carbs. 40% of 2,000 is 800 kcal. Carbs are 4 kcal per gram, so 800 divided by 4 is 200g.

Fat. 30% of 2,000 is 600 kcal. Fat is 9 kcal per gram, so 600 divided by 9 is about 67g.

So on 2,000 kcal, a balanced day is roughly 150g protein, 200g carbs and 67g fat. That is your target. You then log your food and try to land near those numbers by bedtime.

Getting the split right for you

The 30/40/30 split is a sensible default, not a rule carved in stone. A few tweaks people commonly make:

• Trying to hold onto muscle while dieting? Nudge protein up, often to around 1.6 to 2.2g per kilogram of body weight, and pull carbs down to make room.
• Training hard or doing endurance work? More carbs help, since they are your quick fuel.
• Prefer richer, fattier food? Push fat up and carbs down. The calories are what drive weight change, so the split is mostly about what keeps you full and happy enough to stick with it.

Whatever you pick, protein is the one most worth hitting. It keeps you full and protects muscle, which matters most when you are eating less.

Let the app do the arithmetic

Doing 4/4/9 by hand for every meal gets old fast. Fettle (stayfettle.com) sets your macro targets from your calorie goal and adds up the grams as you log, so you can see at a glance how much protein you still need before dinner. It has UK foods and barcode scanning, it is free, and there is no account to bother with.

One honest note

These splits and figures are general guidance, not medical advice. They suit most healthy adults, but if you have a health condition, are pregnant, or follow a specific eating plan for medical reasons, check with your GP or a registered dietitian before changing how you eat.