- Enter starting weight.
- Enter average daily energy balance; use a negative number for a deficit.
- Keep seven days or choose another short period.
- Adjust the energy-equivalent assumption only when you have a reason to do so.
Weekly Weight Estimator
This calculator provides a simple seven-day weight estimate from starting weight and average daily energy balance. It can illustrate the direction and rough scale of change under a fixed planning assumption.
Real weight does not follow a perfect energy conversion because water, glycogen, digestion, and metabolic adaptation can dominate short-term changes. Treat the result as a scenario, not a forecast guarantee.
Weekly weight scenario
kg
kcal/day
days
kcal/kg
Result
—
Estimated ending weight
Estimated change—
Total energy balance—
Direction—
Estimated weight change = daily energy balance × days ÷ energy equivalent
Ending weight = starting weight + estimated change
What the result means
The result is a modeled ending weight under the entered constant energy-balance assumption.
Short-term scale weight may differ substantially because of fluid shifts.
Given: 80 kg, −500 kcal/day for 7 days, 7,700 kcal/kg.
Calculation: −500 × 7 ÷ 7,700 = −0.45 kg.
Result: Estimated ending weight is 79.55 kg.
Why is the energy equivalent adjustable?
The common conversion is only an approximation and real responses vary.
Can I use this for long periods?
Error grows over longer periods because energy expenditure and behavior change.
Why might the scale rise during a deficit?
Water retention, glycogen, sodium, and digestive contents can temporarily offset fat loss.
Should exercise calories be entered separately?
Include them in the net daily energy balance rather than counting them twice.
Is a larger deficit always better?
No. Aggressive deficits may be unsafe or unsustainable and warrant professional guidance.