Review of Intermittent Fasting for Runners

Intermittent fasting (IF) has exploded in popularity for weight management and metabolic health. But how does it fit into the world of running, where energy demand is high?

What Is IF?

Common protocols include 16:8 (fast for 16 hours, eat in an 8-hour window) or alternate-day fasting. For runners, the question is whether training in a fasted state helps or hinders performance.

Benefits

• Fat Adaptation: Running fasted trains the body to burn fat more efficiently.
• Weight Control: Helps some athletes manage body composition.
• Simplicity: Reduces constant snacking and food tracking.
  
  

Risks

• Reduced High-Intensity Performance: Low glycogen makes speedwork tougher.
• Recovery Challenges: Delayed fueling may slow muscle repair.
  
• Risk of Underfueling: Can lead to fatigue, injury, or hormonal disruption.
  
  

Practical Approach

• Use IF on easy run days, not on high-intensity workouts.
  
• Break the fast with a protein- and carb-rich meal.
  
• Monitor energy, mood, and performance closely.
  
  

Verdict

Intermittent fasting can support fat adaptation and weight management, but it’s not ideal for runners prioritizing speed or heavy training loads. Use strategically, not universally.

- Edward