Counting calories alone isn't enough — two diets with the same calories but different macro splits produce very different results in your body. When you set your macros (protein, carbs, fat) correctly, you stay fuller, protect muscle, and reach your goal faster. This guide shows you how to calculate your macros from scratch, step by step.
What Are Macronutrients?
Macronutrients are the three main nutrients your body needs in large amounts for energy. Each has a fixed calorie value per gram:
| Macro | Calories / gram | Main role |
|---|
| Protein | 4 kcal | Muscle repair, satiety, immunity |
| Carbohydrate | 4 kcal | Primary energy, training performance |
| Fat | 9 kcal | Hormones, vitamin absorption, cell structure |
Your total calorie intake equals the sum of these three macros. "Counting macros" means looking not just at total calories, but at how those calories are distributed.
Step 1: Find Your Daily Calorie Needs
Macro math starts with your total daily energy needs (TDEE). TDEE = basal metabolic rate (BMR) × activity factor. The Mifflin-St Jeor equation is one of the most reliable estimates:[1]
🧮 Practical shortcut
To maintain weight, roughly body weight (kg) × 30–33 kcal is a good starting point (moderate activity). For a 70 kg person that's ≈ 2,100–2,300 kcal. To lose weight, subtract 300–500 kcal per day.
Step 2: Split Calories Into Macros
Order matters: set protein first, then fat, then put the remaining calories into carbs.
1
Set Protein First
For an active person aim for 1.6–2.2 g/kg. Example: 70 kg × 1.8 = 126 g protein. That's 126 × 4 = 504 kcal. Protein comes first because it keeps you full and reduces muscle loss.
2
Set Fat
Let 20–35% of total calories come from fat (minimum ~0.5–0.8 g/kg for hormones). On a 2,400 kcal day, 30% = 720 kcal → 720 ÷ 9 = 80 g fat.
3
Put the Rest Into Carbs
Subtract protein and fat calories from your total, then divide by 4. 2,400 − 504 − 720 = 1,176 kcal → 1,176 ÷ 4 = 294 g carbs.
Example: 70 kg, Moderately Active, Maintenance
| Macro | Amount | Calories |
|---|
| Protein | 126 g | 504 kcal |
| Fat | 80 g | 720 kcal |
| Carbohydrate | 294 g | 1,176 kcal |
| Total | — | ≈ 2,400 kcal |
Macro Splits by Goal
Total calories determine the outcome, but the split makes it easier:
- Fat loss: high protein (1.8–2.2 g/kg), fat 20–30%, rest carbs — for satiety and muscle retention.
- Muscle gain: slight surplus (+250–400 kcal), higher carbs (training fuel).
- Maintenance/health: balanced — protein 1.6 g/kg, fat 30%, rest carbs.
💡 Remember
As long as protein and total calories stay fixed, shifting the carb/fat ratio won't meaningfully change your weight result. So pick the split you can sustain.
The Easy Way to Track Macros
The hardest part of macro tracking is weighing every meal and logging it by hand — that's why most people quit. Suu removes that friction:
- 🎙️ Say it: "A chicken breast and a bowl of rice" — Suu extracts the macros.
- 📷 Snap a photo (Premium): AI estimates the portion from your plate and returns calories + macros.
- 📊 Protein, carbs, fat and sodium are written automatically to Apple Health / Health Connect; a 1–100 nutrition score per meal.
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Track macros without weighing grams
Speak or snap a photo; let Suu calculate calories and macros in seconds.
Summary
- Macros: protein (4 kcal/g), carbs (4 kcal/g), fat (9 kcal/g).
- Find daily calories first, then split protein → fat → carbs in that order.
- Protein: 1.6–2.2 g/kg · Fat: 20–35% of calories · Carbs: the remainder.
- With protein and total calories fixed, prioritize a split you can sustain.
- Automate macro tracking with Suu by voice or photo.
Frequently asked questions
What are macros (macronutrients)?
Macronutrients are the three main nutrients your body needs in large amounts for energy and structure: protein (4 kcal/g), carbohydrate (4 kcal/g) and fat (9 kcal/g). Your total calorie intake is the sum of these three macros. 'Counting macros' means looking not only at total calories but also at how those calories are split between the three.
How much protein should I eat per day?
For general health, a minimum of 0.8 g/kg is enough. But if you train regularly, are losing weight, or want to keep/build muscle, aim for 1.6–2.2 g/kg. For a 70 kg active person that's roughly 112–154 g of protein. Protein is the most important macro on a diet because it keeps you full and reduces muscle loss.
How should I split my macros for weight loss?
Total calorie deficit drives fat loss, but macro split makes it easier. A common start: keep protein high (1.8–2.2 g/kg), keep fat at 20–30% of calories, and put the rest into carbs. High protein increases fullness and minimizes muscle loss during a deficit.
Should I cut carbs or fat?
Both have a minimum: fat shouldn't drop below ~0.5–0.8 g/kg (for hormones), and carbs help training performance. The 'right' split is mostly personal preference and sustainability. As long as total calories and protein stay constant, the carb/fat ratio won't meaningfully change your weight outcome.
Do I have to count macros by hand?
No. With Suu you can say your meal out loud ('a chicken breast and a bowl of rice') or snap a photo of your plate; AI estimates the portion and extracts calories and macros in seconds, then writes them to Apple Health. This makes macro tracking practical without weighing grams.
Scientific References
- Mifflin MD, et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. The American Journal of Clinical Nutrition, 51(2), 241–247. PubMed: 2305711
- Morton RW, et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength. British Journal of Sports Medicine, 52(6), 376–384. PubMed: 28698222