Fast Forecast Tool
Preview what to expect during your fast based on your personal parameters. This tool provides estimates based on general research and should not replace medical advice.
1-168 hours (7 days max)
Estimated Ketone Levels (BHB mmol/L)
About Ketone Levels
Ketones (BHB) are produced when your body breaks down fat for energy during fasting. Higher levels indicate deeper nutritional ketosis.
Levels typically range from 0.5-16 mmol/L during fasting, matching common urine test strips.
Learn more
About Ketone Levels
Ketones (BHB) are produced when your body breaks down fat for energy during fasting. Higher levels indicate deeper nutritional ketosis.
Levels typically range from 0.5-16 mmol/L during fasting, matching common urine test strips.
Learn moreKetones are your body's alternative fuel source produced from fat. Higher levels indicate deeper ketosis.
Mental Clarity & Energy Levels
About Mental Clarity & Energy
As your brain adapts to using ketones for fuel, many experience improved focus and stable energy without the typical glucose fluctuations.
Initial dips are common during the metabolic transition period.
Learn more
About Mental Clarity & Energy
As your brain adapts to using ketones for fuel, many experience improved focus and stable energy without the typical glucose fluctuations.
Initial dips are common during the metabolic transition period.
Learn moreMany people report improved mental clarity and stable energy once adapted to using ketones for fuel.
Hunger Levels
About Hunger Patterns
Hunger comes in waves influenced by ghrelin, your hunger hormone. These waves typically decrease in intensity as your fast progresses.
Most people find hunger becomes manageable after the first 24-48 hours.
Learn more
About Hunger Patterns
Hunger comes in waves influenced by ghrelin, your hunger hormone. These waves typically decrease in intensity as your fast progresses.
Most people find hunger becomes manageable after the first 24-48 hours.
Learn moreHunger typically comes in waves and decreases over time as your body adapts to fasting.
Autophagy Activity
About Autophagy
Autophagy is your body's cellular recycling system. During fasting, damaged proteins and organelles are broken down and recycled.
Significant autophagy typically begins after 18-24 hours of fasting.
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About Autophagy
Autophagy is your body's cellular recycling system. During fasting, damaged proteins and organelles are broken down and recycled.
Significant autophagy typically begins after 18-24 hours of fasting.
Learn moreAutophagy is your body's cellular cleanup process that increases significantly during fasting.
Disclaimer: These estimates are based on general research and averages. Individual responses vary significantly. Always consult with healthcare professionals before undertaking extended fasts.