Day 1 — Two Protocols, One Starting Line
Both protocols begin from a normal fed metabolic state.
- 1,090: FMD day-1 intake (kcal, plant-fat rich)
- 0: Water fast intake (kcal, water only)
- ~90: Blood glucose (both) (mg/dL fasting baseline)
- <0.2: Ketones (both) (mmol/L, fed state)
What is a fasting-mimicking diet
Low-calorie, low-protein, plant-fat plan tricking the body into fasting.
What is prolonged water fasting
Zero calories, water only, for multiple consecutive days.
Why compare them side by side
Same fasting biology, very different nutrient and safety profiles.
Early Metabolic Shift — Glycogen Runs Out
Liver glycogen empties on a similar timeline in both protocols.
- ~24 h: Glycogen depletion (similar for both protocols)
- 725: FMD day 2-5 intake (kcal/day)
- Falling: Insulin (both) (as glucose intake drops)
- ~0.2-0.8: Ketone level (both) (mmol/L, rising slowly)
Glycogen as the first fuel reserve
~24 hours of stored glucose burns first, in both protocols.
FMD calorie floor keeps signaling active
Minimal plant fat and sugar still trigger fasting-like signaling.
Water fast has no calorie floor
Zero intake pushes the shift toward fat oxidation faster.
Ketosis Onset — Diverging Curves
Both enter mild ketosis, but the water fast climbs steeper.
- 0.5: FMD ketones day 3 (mmol/L, gradual rise)
- 2.0: Water fast ketones day 3 (mmol/L, steep rise)
- Rising: Autophagy markers (in both protocols)
- Low: FMD protein intake (plant-derived, minimal)
Ketone body production ramps up
Liver converts fat to ketones once glycogen is gone.
FMD ketosis is gentler
Residual plant fat and calories slow the ketone climb.
Water fast ketosis is steep
Zero calories drive faster, deeper ketone body accumulation.
Nutrient & Safety Divergence
Water fasting supplies zero micronutrients, raising medical risk.
- Present: FMD micronutrients (vitamins, minerals included)
- Zero: Water fast micronutrients (no vitamins or minerals)
- 70: Water fast risk score day 4 (of 100, climbing fast)
- 20: FMD risk score day 4 (of 100, stays low)
FMD is formulated with micronutrients
Vitamins and minerals are deliberately included in the plan.
Water fasting has no nutrient buffer
Electrolyte and vitamin depletion accumulates unchecked.
Medical supervision needs differ sharply
Prolonged water fasts warrant closer clinical monitoring.
Day 5 Comparison — Balancing Benefit and Risk
FMD trades some ketosis depth for a much safer profile.
- 0.9: FMD ketones day 5 (mmol/L, moderate)
- 5.0: Water fast ketones day 5 (mmol/L, deep ketosis)
- 22: FMD safety risk day 5 (of 100, low)
- 88: Water fast safety risk day 5 (of 100, high)
Autophagy benefit appears in both
Cellular cleanup activity rises across both five-day protocols.
FMD keeps risk low throughout
Nutrient inclusion keeps the five-day safety score modest.
Water fasting trades safety for depth
Deeper ketosis comes with steeply rising medical risk.