02/17/2026
One of the most common concerns I hear is this: “If I fast, won’t I lose muscle?”
Let’s walk through what actually happens physiologically.
When you eat frequently throughout the day, insulin stays elevated. Elevated insulin keeps the body in storage mode. In this state, fat burning is limited and the body relies primarily on incoming fuel.
During a structured fast, insulin levels drop. When insulin drops, the body shifts into accessing stored energy, primarily body fat. At the same time, another important hormonal shift occurs:
Growth hormone rises significantly. Some research shows up to a 1,300% increase during a block fast. Growth hormone plays several critical roles:
• preserves lean muscle tissue
• increases fat utilization
• supports tissue repair
• contributes to anti-aging pathways
This rise in growth hormone is protective. It signals the body to maintain lean tissue while utilizing stored fat for fuel.
The body is designed to adapt during periods without food. It does not immediately break down muscle when a meal is skipped. Instead, it prioritizes stored energy and protects essential tissues.
This is part of what we call metabolic flexibility, the ability to efficiently switch between burning glucose and burning fat. Many people today have lost this flexibility because they rarely enter a true fasted state.
Structured fasting helps restore that adaptability.
It is not about starvation.
It is not about muscle loss.
It is about allowing the body to move through natural metabolic cycles.
When implemented appropriately and followed by intentional refeeding, fasting can support improved body composition, reducing fat while preserving muscle.
If this clarified how fasting works at a hormonal level, share it with someone who believes fasting automatically causes muscle loss.