How to Calculate Calories and Macros for Weight Loss
There are thousands of diet systems, but only one principle underneath them all: to lose fat, you have to eat fewer calories than you burn, consistently, for long enough. Everything else — keto, paleo, intermittent fasting, carnivore, carb cycling — is a different delivery mechanism for the same equation.
This guide shows you how to work out your maintenance calories (TDEE), how big of a deficit is realistic, and how to split those calories between protein, carbs, and fat. The numbers use the same formula as our Calorie Calculator so you can verify any step.
✨Key takeaways
- BMR = what your body burns at rest. TDEE = BMR × an activity multiplier.
- A daily deficit of 300–750 kcal below TDEE produces ~0.3–0.7 kg (0.75–1.5 lb) of fat loss per week.
- Protein should be the anchor: aim for ~1.6–2.2 g per kilogram of body weight.
- Weigh yourself daily but trust only the 7-day average — water fluctuations can mask real progress.
Step 1: BMR with the Mifflin-St Jeor equation
Basal Metabolic Rate is the calories you burn if you did absolutely nothing all day. The Mifflin-St Jeor formula is the current gold standard for estimating it.
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Example: a 32-year-old woman who is 165 cm and 70 kg. BMR = 10 × 70 + 6.25 × 165 − 5 × 32 − 161 = 700 + 1,031.25 − 160 − 161 ≈ 1,410 kcal/day.
Step 2: TDEE using an activity multiplier
Multiply BMR by the factor that best describes your week:
• Sedentary (desk job, little exercise): 1.2
• Lightly active (1–3 sessions/week): 1.375
• Moderately active (3–5 sessions/week): 1.55
• Very active (6–7 sessions/week): 1.725
• Extra active (manual labour + training): 1.9
Continuing the example: a 1,410 BMR at moderate activity gives 1,410 × 1.55 ≈ 2,186 kcal/day. That is her maintenance — the calorie level at which her weight should remain roughly stable.
Step 3: Pick an honest deficit
A deficit of 500 kcal/day produces about 0.5 kg (1 lb) of fat loss per week, assuming 1 kg of fat stores roughly 7,700 kcal. For most adults, that is a comfortable, sustainable pace.
Our example dieter at 2,186 TDEE drops to a 1,686 kcal/day target. Anything below about 1,200–1,400 kcal/day for women or 1,500–1,800 for men makes nutrient targets difficult and hunger sky-high.
If weight loss stalls for more than two weeks despite honest logging, drop by another 100–150 kcal — not by slashing 500 more at once, which just makes adherence harder.
Step 4: Divide the calories into macros
Protein first. Use 1.6–2.2 g/kg of body weight. For our 70 kg example, that is 112–154 g/day. Set it at 140 g → 140 × 4 = 560 kcal from protein.
Fat next. Set it at 0.6–1.0 g/kg. For 70 kg, that is 42–70 g/day. Use 60 g → 60 × 9 = 540 kcal.
Carbs fill the remainder. Total target is 1,686. Subtract 560 (protein) + 540 (fat) = 1,100 kcal → 1,100 ÷ 4 = 275 g of carbs.
So the example dieter aims for roughly 140 g protein / 60 g fat / 275 g carbs, all totalling 1,686 kcal a day. Use the Calorie Calculator to generate the same targets for your own stats.
Step 5: Track, measure, and adjust weekly
Weigh yourself first thing in the morning, undressed, after the bathroom — and only trust the 7-day rolling average. Single-day jumps of 1–2 kg are almost always water, not fat.
If the 7-day average does not drop for 2–3 weeks, cut an extra 100–150 kcal a day or add a little activity. If it drops too fast (more than ~1% of body weight per week on average), eat a little more — crash diets tank energy, training, and often lead to rebound.
The three mistakes that stall progress
Under-logging by eye. Oils, dressings, sauces, and "bites" add up fast. A food scale is the single most-accurate tool you own — use one for at least the first month.
Ignoring weekends. Three days of loose tracking can wipe out four days of a 500 kcal deficit. Aim for consistency across the full week.
Chasing the scale obsessively. Body weight fluctuates with salt, carbs, menstrual cycle, training soreness, and sleep. Trust the trend, not any one day.
Try the calculators referenced in this guide
Put the maths into practice — every calculator is free and runs entirely in your browser.
Frequently Asked Questions
Can I lose fat without counting calories?
Yes — prioritising whole foods, protein at every meal, and eating slowly often creates a natural deficit. Counting just makes the invisible visible and is useful if progress stalls.
How much protein is too much?
For healthy adults, research has found no meaningful downside up to roughly 3.3 g/kg of body weight. The practical question is usually cost and digestion, not safety.
Do I need to cut carbs to lose fat?
No. Meta-analyses comparing low-carb, low-fat, and mixed diets find similar fat loss at equated calories and protein. Pick the approach you can stick to.
Is my BMI relevant for weight-loss targets?
It is a reasonable screening tool for most adults. Pair it with the BMI Calculator and a tape measure. If you are very muscular or very lean, BMI may misclassify you — body-fat percentage is a better measure.
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