Fasting. What It Actually Does.

• Lowers insulin — the body's main storage signal.
• Reduces mTOR activity — the body's main growth signal.
• When both are low, the body shifts from building mode into repair mode, including autophagy — its cellular cleanup process.

• Autophagy increases progressively, becoming significant after roughly 24 hours. This applies to everyone, regardless of diet.
• Metabolic health affects how quickly this happens — insulin resistance blunts and delays the autophagy response.
• A high-carb diet runs high insulin most of the day — fasting is the main way to bring it down.
• An animal based or low-carb diet already runs low insulin most of the day — often producing ketosis, the same fat-burning state fasting induces. Fasting adds less here.
• High protein intake can blunt ketosis — the liver converts excess amino acids to glucose through gluconeogenesis. Even on a carnivore diet, insulin may be higher than expected — fasting still has a role here.
• Protein also activates mTOR independently of insulin. A high-protein animal based diet can keep mTOR elevated even when insulin is low — fasting still has a role here.

Start with 16 hours. Then 24. Build from there. A 72-hour fast is not a starting point.

• Day 1 is the hardest — hunger waves, the urge to eat out of habit rather than need. They pass. Push through.
• Day 2 something shifts — a quiet calm replaces the noise. Mental clarity arrives.
• Day 3 the clarity deepens. The constant preoccupation with food — what to eat, when to eat, where to eat — simply stops.

Exercise during a fast is fine — keep it light to moderate. Intense sessions are harder to recover from without food. Listen to your body.