What Is a Weekly Calorie Deficit?
A calorie deficit happens when you burn more energy than you consume. Your daily deficit is simply your Total Daily Energy Expenditure (TDEE) minus the calories you eat. Sustaining that deficit over a week produces measurable fat loss. This calculator turns your numbers into a clear estimate of how fast you might lose weight.
How to Use It
Enter your TDEE (the calories your body burns in a day) and your average daily calorie intake. The tool computes your daily deficit, multiplies it by seven for the weekly total, and converts that energy into kilograms and pounds of expected fat loss.
The Formula Explained
Roughly 7,700 kcal is stored in one kilogram of body fat (about 3,500 kcal per pound). So the weekly loss in kg equals the daily deficit times seven, divided by 7,700:
$$\text{weekly\_loss\_kg} = \frac{(\text{daily\_deficit} \times 7)}{7700}$$
This is an estimate — real-world results vary with water weight, muscle changes, and metabolic adaptation.
Worked Example
Suppose your TDEE is 2,200 kcal and you eat 1,700 kcal per day. Your daily deficit is \(2200 - 1700 = 500\) kcal. Over a week that's 3,500 kcal. Dividing by 7,700 gives about 0.45 kg (roughly 1 lb) of fat loss per week — a safe, sustainable pace.
$$\frac{(2200 - 1700) \times 7}{7700} \approx 0.45 \text{ kg}$$FAQ
How big should my deficit be? A 300–700 kcal daily deficit is commonly recommended for steady, sustainable loss of about 0.3–0.6 kg per week.
Why kg and pounds differ slightly? 7,700 kcal/kg and 3,500 kcal/lb are standard estimates; both are approximations of fat energy density.
Is faster always better? No. Very aggressive deficits can cause muscle loss, fatigue, and rebound. Pair a moderate deficit with adequate protein and strength training.
