November 19, 2025

Episode 3: Should Athletes Fast? The Performance vs. Weight Loss Dilemma

46 minutes

In the final episode of the fasting series, Simon and Dr. Jules Strauss tackle the complex question of whether endurance athletes should fast, and if so, how to do it safely without compromising training quality or health.

Jules brings her expertise in sports nutrition to provide practical guidance on timing fasting protocols around training seasons, the difference between fasting for weight loss and fasted training for metabolic adaptation, and how to monitor whether a fasting approach is helping or hindering performance.

Key Points Discussed:

Should endurance athletes fast?

It depends on individual circumstances, but fasting is not a performance enhancer - it's about careful management to maintain performance while pursuing other goals.

Timing within the training year:

Off-season is ideal for experimenting with fasting protocols, while build phases, competition prep, and race periods should avoid restrictive approaches.

The planning complexity:

How fasting requires more careful attention to meeting macronutrient needs (6-7g carbs/kg, 1.6-2.2g protein/kg) within restricted eating windows.

Fasted training vs. fasting protocols:

The difference between acute fasted training sessions (for metabolic flexibility) and chronic fasting approaches (for weight management).

Monitoring and red flags:

How to track whether fasting is working through training metrics, recovery markers, immune function, and menstrual health in females.

The performance-health-body composition triangle:

Jules' framework for balancing competing priorities and staying within the "sweet spot" of all three goals.

Key Quotation:

"I think the key thing to recognise is that this (fasting) isn't going to be a performance enhancer. This isn't an approach that an athlete should pursue from an improved performance perspective. That's not to say that we can't maintain our performance if we carefully manage a fasting approach"

— Dr. Jules Strauss

Connect with Dr. Jules Strauss:

Website: totalendurancenutrition.com

Instagram: @drjulesstrauss_nutritionist

If you are training for endurance sport and tempted by fasting please check out this research first:

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By Simon Ward

4.5

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