Episode 1: Understanding Fasting and Nutrition - The Science Behind What Happens When We Fast

In this first episode of our three-part fasting series, Simon Ward welcomes Dr. Jules Strauss to explore the evolutionary science behind fasting and what actually happens in our bodies when we restrict food intake. While fasting has become a popular topic on social media, Jules brings her decade of research in exercise metabolism to separate the science from the hype.

Together, they unpack how our hunter-gatherer ancestors evolved to handle periods without food, the hour-by-hour changes that occur during fasting, and why our relationship with hunger is far more complex than we might think.

Key Points Discussed:

1. Our evolutionary relationship with fasting:
   Humans evolved with intermittent access to food, developing metabolic flexibility to switch between glucose and fat burning during feast and famine cycles.
2. The fasting timeline - what happens hour by hour:
   From overnight fasting (insulin drops, fat burning begins) to extended fasting (liver glycogen depletion, ketone production) and the physiological stress responses that occur.
3. Understanding hunger signals:
   How appetite hormones like ghrelin and satiety signals work, why hunger often disappears during fasting, and the difference between true hunger and habitual eating patterns.
4. The real benefits backed by science:
   Improvements in insulin sensitivity, glucose control, and body composition - but with the important caveat that most studies are done on metabolically unhealthy populations, not athletes.
5. Fasting as physiological stress:
   Why fasting increases cortisol and adrenaline, and how this compounds with training stress in athletes.

Key Quotation:

"We all typically will fast overnight, and you know, depending on bedtime and waking time, the duration of that overnight fast that we all have will be slightly variable... but ultimately, that overnight fast will mean that we lean slightly more towards fat metabolism." 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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