Enter the estimated daily calorie deficit during the fast (Calories/day, i.e., kcal/day) and the days of water fast into the Water Fast Weight Loss Calculator. The calculator estimates approximate fat loss from the energy deficit; actual scale weight change during a fast can differ substantially due to water/glycogen shifts and other factors.
Water Fast Weight Loss Formula
The following example problem outlines the steps and information needed to calculate the Water Fast Weight Loss (as an estimate of fat loss from an energy deficit).
WFL = \frac{DC \times D}{3500}Variables:
- WFL is the estimated fat loss from the fast (lb)
- DC is the estimated daily calorie deficit during the fast (Calories/day, i.e., kcal/day)
- D is the days of water fast
To estimate fat loss from an energy deficit during a water fast, multiply the length of the fast by your estimated daily calorie deficit, then divide by about 3,500 Calories per pound of body fat (a common rule of thumb). This does not directly predict total scale weight change during a fast.
How to Calculate Water Fast Weight Loss?
The following steps outline how to calculate the Water Fast Weight Loss.
- First, estimate the daily calorie deficit during the fast (Calories/day).
- Next, determine the days of water fast.
- Next, gather the formula from above: WFL = (DC × D) ÷ 3,500.
- Finally, calculate the Water Fast Weight Loss (estimated fat loss).
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
daily calorie deficit (Calories/day) = 2500
days of water fast = 15
WFL = (DC × D) ÷ 3,500 = (2500 × 15) ÷ 3,500 = 10.71 lb (estimated fat loss)
