During a dry fast, you consume nothing at all — no food and no liquids. This is unlike a water fast, where you avoid calories but can drink freely: water, black coffee, unsweetened tea.
By some measures, 1 day of dry fasting delivers the same metabolic benefit as 3 days of water fasting.
The effect varies between individuals — so the app includes an adjustable multiplier specifically for dry fasts. If you’ve observed or believe that dry fasting is 3× more effective than water fasting for you, set the multiplier to 3.
As an example, the app’s author has observed that his muscle mass loss is 2.6 times lower during dry fasts compared to water fasts. Since muscle preservation is his most important metric, he sets the multiplier at 2.6.
By empirical observation, in everyday situations without intense cardio, a dry fast feels about the same as a water fast — but with amplified effects, which include:
- Preserving muscle mass better (roughly 2× less muscle loss during dry fasts)
- Increased immune response, as dry fasting helps eliminate harmful bacteria
- Accelerated fat burn, since the body must burn fat not only for energy but also to produce the water it needs for biological processes
The app includes a toggle to track dry fasting, including when it’s part of a longer fast that combines both dry and water phases.