GKI & Autophagy Calculator.
Map your fasting hours to the cellular stage you're in, and (optionally) compute your exact Glucose-Ketone Index from blood readings.
Insulin drops, glucagon rises.
Liver glycogen runs low. AMPK activates in response to nutrient scarcity. Autophagy pathways begin to engage.
Medical Disclaimer
Extended fasting and ketogenic protocols carry real medical risk for people with diabetes, eating disorder history, pregnancy, or on certain medications. Consult a physician before fasts beyond 24 hours.
How the Math Works
The Glucose-Ketone Index reduces two metabolic markers to a single number. It was originally proposed by Thomas Seyfried's group to track patients on therapeutic ketogenic diets.
- 01Convert glucose units. If glucose is in mg/dL (US standard), divide by 18.016 to convert to mmol/L. If you already report in mmol/L (rest of the world), skip this step.
- 02Compute GKI. GKI = glucose (mmol/L) / ketones (mmol/L). Both have to be in the same units for the ratio to be dimensionless.
- 03Locate band. GKI < 1 = peak therapeutic. 1–3 = high therapeutic. 3–6 = moderate. 6–9 = mild. >9 = no ketosis.
- 04Map fasting hours. Independently of GKI, the calculator maps elapsed fasting time to the four canonical autophagy stages: fed (0–12h), glycogen depletion (12–24h), active autophagy (24–48h), peak (48–72h).
Worked Example
Frequently Asked Questions
What is the Glucose-Ketone Index (GKI)?+
GKI is the ratio of blood glucose (in mmol/L) to blood ketones (also in mmol/L). It is used in clinical research and metabolic therapy as a single number that summarises how deeply someone is in ketosis. A lower GKI means deeper ketosis.
What is a good GKI for autophagy?+
Most research links GKI < 3 with active autophagy, GKI < 1 with peak cellular recycling. GKI > 9 means you are not in therapeutic ketosis. The exact value depends on protocol — Thomas Seyfried's cancer research targets GKI 1–2.
How many hours of fasting until autophagy starts?+
Autophagy is a gradient, not a switch. AMPK signalling and early autophagy markers appear around 16–18 hours of fasting. Deeper, more therapeutic autophagy ramps up after 24 hours, and peaks around 48–72 hours.
Do I need glucose and ketone meters to use this tool?+
No. If you only know your fasting hours, the tool maps you to the autophagy stage. If you also have a glucose and ketone meter, you can additionally compute your exact GKI for more precise tracking.
Why mg/dL versus mmol/L for glucose?+
The US standard reports glucose in mg/dL, while most of the world uses mmol/L. The GKI formula requires mmol/L, so we divide US-style readings by 18.016 (the molar mass conversion factor for glucose) before computing.
Is extended fasting safe?+
For most healthy adults, fasts up to 24 hours are safe. Fasts beyond 48 hours, anyone with diabetes, anyone on medication, pregnant women, or those with eating-disorder history should only fast under medical supervision.