“Stress Is One of the Biggest Issues We’ve Got”: How Stress Undermines Health and Training — Dr. Richard MacKenzie (#18)

Dr. Richard MacKenzie is an associate professor specializing in human metabolism and a clinician working at the intersection of exercise physiology, metabolic health, and stress. He is the author of Stress Tested: How The New Science of Stress Hormones Can Transform Your Health.

In this episode, Richard unpacks what stress actually is from a physiological perspective, how acute and chronic stress differ, and why chronic stress can quietly undermine insulin sensitivity, recovery, sleep, and training adaptations.

We also explore how stress shows up in metrics like heart rate variability, glucose variability, and fuel metabolism, why mindset and perception dramatically alter stress responses, and how exercise, nutrition, caffeine, sleep, and even cold exposure can either buffer or amplify stress.

Episode breakdown:

00:00 – Who is Dr. Richard MacKenzie?

00:16 – Why write Stress Tested now?

02:23 – What is stress?

04:28 – When does stress turn from helpful to harmful?

04:52 – How does chronic stress show up day to day?

06:15 – Can stress actually be measured?

07:41 – What does a personal “stress dashboard” look like?

09:59 – How changeable is stress with mindset?

13:59 – Does exercise reduce stress—or add to it?

15:29 – Is stress one of our biggest health threats?

19:56 – What hidden stressors are we missing?

26:06 – Can diet increase—or reduce—stress?

36:04 – What has stress research changed for Richard?

41:05 – What’s next: protein, metabolism, and future research?

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