Water Fast Weight Loss Calculator
Estimate weight loss during a water fast based on your basal metabolic rate and fasting duration.
Published by:
isCalculator Editorial Team
Was this calculator helpful?
How to use this tool?
Follow these steps to estimate your weight loss during a water fast:
- Enter your age (1–120 years).
- Enter your weight in kilograms (20–500 kg).
- Enter your height in centimeters (50–300 cm).
- Select your gender (Male or Female).
- Set the fasting duration in days (1–30 days).
- Choose your activity level (from Sedentary to Very Active).
- Click Calculate Weight Loss.
The result shows estimated fat loss in kg based on your BMR (Mifflin-St Jeor equation), activity multiplier, and a zero-calorie intake. All inputs must be in metric units (kg, cm). Actual results may vary due to water loss and other factors.
Previous Results
| Result | Inputs | Date |
|---|
Frequently Asked Questions
This calculator provides an estimate based on your BMR and activity level. Actual weight loss can vary due to water loss, glycogen depletion, and individual metabolic differences.
We use the Mifflin-St Jeor equation to estimate BMR, then multiply by an activity factor to get TDEE. The total calorie deficit over the fasting period is divided by 7700 (kcal per kg of fat) to estimate weight loss.
This calculator supports up to 30 days for safety. Longer fasts should only be done under medical supervision.
