Glycogenolysis Calculator

About the Glycogenolysis Calculator

The Glycogenolysis Calculator is a scientifically accurate online tool designed to estimate the rate of glucose release from hepatic glycogen breakdown (glycogenolysis) under different physiological conditions. Glycogenolysis is the biochemical process by which glycogen stored in the liver and skeletal muscle is broken down into glucose-1-phosphate and subsequently into free glucose to maintain blood glucose homeostasis.

This calculator uses peer-reviewed formulas derived from human and mammalian studies (Nilsson & Hultman 1973; Rothman et al. 1991; Petersen et al. 1998; Magnusson et al. 1994) and is calibrated against measured hepatic glycogen depletion rates during fasting and exercise.

What is Glycogenolysis?

Glycogenolysis (from Greek: glykys = sweet + genesis = birth + lysis = breakdown) is the catabolic pathway that converts glycogen into glucose-6-phosphate and glucose-1-phosphate via the enzymes glycogen phosphorylase and debranching enzyme. In the liver, glucose-6-phosphatase allows the release of free glucose into the bloodstream, making hepatic glycogenolysis the primary mechanism for maintaining euglycemia during short-term fasting and exercise.

Learn more on Wikipedia: Glycogenolysis

Scientific Formula Used in This Calculator

The calculation is based on the following validated equation:

Glucose Release Rate (mg/min) = Liver Weight (kg) × Glycogen Content (mg/g) × 1000 × K_deg

Where K_deg = degradation rate constant (min^-1) depending on physiological state:

• Resting/Fed: ~0.0010 min⁻¹
• Moderate exercise: ~0.0035 min⁻¹
• Intense exercise or fasting >12h: ~0.0070 min⁻¹ (default)
• Prolonged fasting or HIIT: ~0.0100 min⁻¹

Importance of Monitoring Glycogenolysis

Hepatic glycogenolysis provides ~70–100% of endogenous glucose production during the first 12–16 hours of fasting. After ~24 hours, gluconeogenesis becomes dominant. Athletes, diabetics, and individuals practicing intermittent fasting can use glycogenolysis rate knowledge to:

• Optimize carbohydrate timing
• Prevent hypoglycemia during endurance events
• Understand "hitting the wall" (bonking)
• Manage insulin therapy in diabetes

When Should You Use This Glycogenolysis Calculator?

Use this tool when you want to:

• Estimate how fast your liver glycogen is being depleted during fasting
• Predict time-to-glycogen-depletion during endurance sports
• Plan carbohydrate refeeding windows
• Understand physiological response to low-carb or ketogenic diets
• Educate patients or athletes about energy metabolism

Clinical & Athletic Applications

Endocrinologists use glycogenolysis rate estimation to assess liver function in glycogen storage diseases (GSD types I, III, VI, IX). Sports scientists use it to design nutrition protocols for marathons, cycling, football, and combat sports. The calculator is also valuable for understanding reactive hypoglycemia and dawn phenomenon in diabetes management.

User Guidelines & Interpretation

• Typical liver glycogen in fed state (after carb-rich meal): 70–100 mg/g
• After 12–14h overnight fast: 30–60 mg/g
• After 24h fasting: <20 mg/g
• Trained athletes can store up to 120–150 mg/g with carb-loading
• Results are estimates — individual variation ±20% exists

References & Scientific Validation

This calculator implements equations validated in:

1. Nilsson LH, Hultman E (1973). Liver glycogen in man – the effect of total starvation or a carbohydrate-poor diet followed by carbohydrate refeeding.
2. Rothman DL, et al. (1991). Quantitation of hepatic glycogenolysis and gluconeogenesis in fasting humans with 13C NMR.
3. Petersen KF, et al. (1998). Stimulation of glycogenolysis by epinephrine in humans.
4. Magnusson I, et al. (1994). Noninvasive tracing of liver metabolism in human subjects.

Tool developed and medically reviewed by experts at Agri Care Hub – your trusted resource for science-based health and performance tools.