If you've spent any time in health and fitness circles, you've probably encountered the word "macros". People talk about hitting their macros, calculating their macros, and blaming their macros when results aren't coming. But what are macros, exactly? And do you actually need to track them, or is it just another layer of complexity that fitness culture has invented to keep you confused?
What Are Macros?
Macros — short for macronutrients — are the three main categories of food that provide energy: protein, carbohydrates, and fat. Alcohol is sometimes counted as a fourth macro, but it's generally not something you'd deliberately plan around.
- Protein: 4 calories per gram — builds and repairs muscle, supports immune function, keeps you feeling full
- Carbohydrates: 4 calories per gram — your body's preferred energy source, fuels the brain and muscles
- Fat: 9 calories per gram — essential for hormone production, brain function, and absorbing fat-soluble vitamins
All three are essential. Anyone who tells you to eliminate an entire macro is selling you something. Use our macro calculator to set targets appropriate for your goals and body.
Why Track Macros Instead of Just Calories?
Calorie counting gets you to the right total energy. Macro tracking ensures the right quality and composition of that energy. Two people eating 2,000 calories can have very different results depending on how those calories are split:
- Person A: 2,000 calories — 150g protein, 200g carbs, 65g fat (muscle-building friendly)
- Person B: 2,000 calories — 50g protein, 300g carbs, 80g fat (likely to lose more muscle if in a deficit)
If your goals include building muscle, preserving lean mass while losing fat, or optimising athletic performance, macros matter beyond just total calories.
Setting Your Macros: Where to Start
Your starting point is always your total calorie target (from your TDEE). Then you divide those calories between the three macros.
Protein is usually set first because it's the most important for body composition. A good general target is 1.6-2.2g of protein per kilogram of body weight. For a 75kg person, that's 120-165g of protein per day. Protein calories: multiply grams by 4.
Our calorie deficit calculator and macro calculator work together — start with calories, then dial in your macro split.
Common Macro Splits
General guidance for different goals:
- Weight loss (preserving muscle): 30-35% protein, 30-35% carbs, 30-35% fat
- Muscle building: 25-30% protein, 45-55% carbs, 20-25% fat
- Endurance athletes: 20-25% protein, 55-65% carbs, 15-20% fat
- Low-carb/keto: 25-30% protein, 5-10% carbs, 65-70% fat
These are starting points, not commandments. Individual responses vary — some people do better on higher carbs, others prefer more fat. Experiment and track results over 4-6 week blocks.
Protein: Why It Gets the Most Attention
Protein has the highest thermic effect of food — your body burns more energy digesting protein than carbs or fat (roughly 20-30% vs 5-10% for carbs and 0-3% for fat). It's also the most satiating macro, meaning it keeps you fuller for longer. And critically for people in a calorie deficit, adequate protein intake preserves muscle mass — so the weight you lose is primarily fat.
Carbohydrates: Not the Enemy
Carbohydrates have been demonised in diet culture for decades, but they're your body's preferred fuel source — particularly for the brain and high-intensity exercise. The quality matters more than the quantity: whole grains, legumes, fruits, and vegetables provide fibre and micronutrients alongside the energy. Refined sugars and ultra-processed carbs lack these benefits.
How to Track Macros in Practice
An app like MyFitnessPal, Cronometer, or Nutracheck makes tracking practical. Scan barcodes, log portions, and the app does the arithmetic. The first two weeks feel tedious; after that it becomes quick and intuitive. Most people who track macros for 6-8 weeks build such a strong understanding of food composition that they can estimate accurately without an app.
You don't need to track macros forever. But doing it for a few months builds nutritional literacy that lasts a lifetime.
Further reading: The British Nutrition Foundation has well-referenced guidance on macronutrients and a healthy diet. Visit the British Nutrition Foundation's dietary guidance.