Weight loss comes down to one simple principle: eat fewer calories than you burn. But how many fewer? And how do you calculate the right number for your body?
The short answer: A deficit of 500 calories/day leads to roughly 0.5kg (1lb) weight loss per week. A 1,000 calorie deficit leads to ~1kg/week. NHS and CDC both recommend the slower approach for sustainable results.
Your Total Daily Energy Expenditure (TDEE) is how many calories your body burns each day — including exercise. This is your maintenance level.
TDEE is calculated from your Basal Metabolic Rate (BMR) — the calories you burn at rest — multiplied by your activity level.
The most accurate formula is Mifflin-St Jeor:
Then multiply by activity factor: Sedentary (1.2), Light (1.375), Moderate (1.55), Very Active (1.725).
Skip the maths — our calorie calculator does this for you instantly.
🔥 Calculate My Calories| Goal | Daily Deficit | Weekly Loss |
|---|---|---|
| Slow & sustainable | 300–500 kcal | 0.25–0.5kg (0.5–1lb) |
| Standard | 500–750 kcal | 0.5–0.75kg (1–1.5lb) |
| Aggressive (not recommended long-term) | 750–1000 kcal | 0.75–1kg (1.5–2lb) |
Never go below these levels without medical supervision — doing so risks muscle loss, nutrient deficiencies and metabolic slowdown:
When losing weight, your body can break down muscle as well as fat for energy. Eating 1.6–2.2g of protein per kg of body weight while in a deficit is the most evidence-backed way to preserve muscle mass.
For a 75kg person, that's 120–165g of protein daily. Prioritise: chicken, fish, eggs, Greek yoghurt, cottage cheese, legumes, tofu.
As you lose weight, your TDEE decreases — you're a smaller person burning fewer calories. This is why progress slows. Solutions:
Calculate your BMI alongside your calorie target for a full picture of your health goals.
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