Macros — short for macronutrients — are the three main components of every food you eat: protein, carbohydrates, and fat. Understanding them is the foundation of eating well, whether your goal is losing weight, building muscle, or simply feeling better day to day.
This guide explains what macros are, how to work out your targets, and how to track them simply using UK foods and apps that work for UK supermarket products.
What are macros and why do they matter
Every food is made up of some combination of protein, carbohydrates, and fat. These three macronutrients provide all of your dietary calories:
- Protein: 4 calories per gram. Builds and repairs muscle, keeps you full, essential for body composition.
- Carbohydrates: 4 calories per gram. Your body's primary energy source. Includes sugars and starches.
- Fat: 9 calories per gram. Essential for hormone production, brain function, and absorbing fat-soluble vitamins.
Total calories = (protein grams × 4) + (carbs grams × 4) + (fat grams × 9).
Calories determine whether you lose, maintain, or gain weight. Macros determine what that weight change is made up of — fat, muscle, or both. Two people can eat the same number of calories and have very different body composition outcomes depending on how much protein they eat and how they train.
How to calculate your macro targets
Step 1: Work out your maintenance calories (TDEE)
Your Total Daily Energy Expenditure is the number of calories your body burns in a day. A rough formula:
- Sedentary (desk job, minimal exercise): bodyweight in kg × 28–30
- Moderately active (3–4 sessions/week): bodyweight in kg × 32–35
- Very active (5+ sessions/week): bodyweight in kg × 36–40
Example: 75kg person, moderately active → ~75 × 33 = ~2,475 calories/day to maintain weight.
Step 2: Set your calorie target
- Fat loss: subtract 300–500 calories from maintenance (avoid going lower — it's unsustainable)
- Muscle gain: add 200–300 calories above maintenance
- Maintenance: stay at TDEE
Step 3: Set protein first
Aim for 1.6–2.2g protein per kg of bodyweight. For the 75kg example: 120–165g protein per day. Set this first — it's the most important macro for body composition.
Step 4: Fill remaining calories with carbs and fat
No fixed rule here. A practical starting split for most people: roughly 30% protein, 40% carbs, 30% fat. Adjust based on preference, energy levels, and satiety.
How to track macros in the UK
The most practical tools for UK-based macro tracking:
MyFitnessPal — the most widely used tracking app in the UK. Has a large UK food database including most supermarket own-brand products and UK restaurant chains. Free version is sufficient for basic tracking.
Nutracheck — UK-specific app with an extensive database of UK supermarket foods. Often more accurate for UK products than MyFitnessPal. Paid subscription (~£7.99/month) but more reliable for UK-specific items.
Cronometer — free, highly accurate, good for people who want detailed micronutrient data alongside macros.
For meal prepping, tracking is simpler — you calculate the macros for a full batch once, divide by the number of portions, and you know the macros for every container. You don't need to re-enter anything during the week.
Common macro tracking mistakes to avoid
Tracking inconsistently. Tracking Monday to Thursday then stopping over the weekend defeats the purpose. Weekends tend to be where most people go over their calorie target — tracking consistently through the week including weekends gives you accurate data.
Not weighing food. "A handful of oats" or "a big scoop of peanut butter" introduces significant error. Use a cheap kitchen scale (under £10 on Amazon) for the first few weeks until you've calibrated your eye for portion sizes.
Obsessing over perfect numbers. Being within 10% of your targets consistently is far more effective than being exactly on target some days and abandoning tracking when you go over. Consistency over time matters more than precision on any given day.
Ignoring liquid calories. Milk, juice, sports drinks, and alcohol all contain calories and macros. Track them.
Macro and nutrition guides
Practical macro guides, calorie-counted UK meal plans, and budget-friendly high-protein recipes are linked below.