What if cortisol isn't the reason you can't lose weight — and your metabolism isn't broken either?
Michelle MacDonald brings back nutrition scientist and coach Dr. Allan Bacon for a conversation that dismantles two of the most persistent myths circulating in women's fitness right now.
Together they break down exactly what cortisol is actually doing in your body during exercise, why zone two cardio lowers cortisol for the rest of the day even though it raises it for two hours (and why no one selling you a supplement is going to show you that part of the graph), and why elevated cortisol simply cannot prevent fat loss when you're in a calorie deficit: because there's nothing left to store.
They also dig into the landmark Pontzer research tracking resting metabolic rate in thousands of men and women from ages 20 to 63, including through the menopause transition, and what it actually shows about metabolism, muscle loss, and the claims being made by wellness influencers selling mushroom tea.
Then they get practical, covering calorie tracking errors, raw vs. cooked food measurements, pre-planning meals, and the three things Dr. Bacon tells every client who has been doing everything right and still isn't seeing results. This episode is for anyone who has been told their hormones are working against them and is starting to wonder if there's a simpler explanation.
Favorite Moments*
- 2:10 What Cortisol Is Actually Doing — and What It Isn't
- 3:27 Cortisol Spikes During Exercise Are a Feature, Not a Bug
- 4:46 Zone Two vs. HIIT: Why Both Get Fear-Mongered for the Same Hormone
- 5:57 Cortisol Is Both a Fat-Storing and a Fat-Burning Hormone (and Supplement Sellers Only Tell You Half the Story)
- 7:57 Zone Two Cardio Raises Cortisol for Two Hours — Then Lowers It Below Baseline for the Rest of the Day
- 21:19 "If You Really Want to Spike Your Cortisol, Worry About Cortisol"
- 24:45 The Pontzer Research: Resting Metabolic Rate Doesn't Change From Age 20 to 63
- 28:14 The Swan Study's "Double Muscle Loss" Claim — What the Actual Numbers Look Like
- 36:30 Calorie Tracking Errors: The Average Person Is Off by 500 Calories a Day
- 40:26 Raw vs. Cooked: The Measurement Mistake Almost Everyone Makes
- 52:18 The Three-Part Audit for Anyone Who Isn't Seeing Progress
- 56:00 Motivation Is the Result of Action, Not the Cause of It
- 58:54 Why Intensity Becomes the Name of the Game After Newbie Gains Are Gone
- 59:57 Stretching Reduces Injury Risk 0 to 4%. Strength Training: Up to 69%
"If you really want to spike your cortisol, worry about cortisol. If you want to not spike your cortisol, learn when it works for you, when it works against you, get rid of the extra stress, and start progressing."
— Dr. Allan Bacon
About Dr. Allan Bacon:
Nutrition & Fitness Coach | Researcher
Instagram: https://www.instagram.com/drallanbacon/?hl=en
YouTube: https://www.youtube.com/channel/UC8vX4qjwi9WTr5sIqxKAXeA
Dr. Allan Bacon is a nutrition scientist, researcher, and coach known for cutting through fitness misinformation without stripping away the nuance. He has collaborated with some of the most respected names in exercise science and brings both the research depth and the real-world coaching experience to show clients not just what the data says — but what it actually means for their training, their diet, and their results. He and his wife coach together and are regular voices in the evidence-based fitness space.
About Michelle MacDonald:
Michelle MacDonald is the creator of the FITNESS MODEL BLUEPRINT™ and host of the Stronger By Design™ podcast. Known globally for her transformation programs, Michelle empowers women to redefine aging through evidence-based strength training, nutrition, and mindset practices. Since 2012, she has coached thousands of women online, leveraging her expertise as a Physique Champion and ISSA Strength and Conditioning Specialist. She co-founded Tulum Strength Club and established The Wonder Women (TWW), inspiring countless transformations including her mother, Joan MacDonald (Train With Joan™). Michelle continues to lead the charge in women's fitness, launching the Stronger by Design™ fitness app in fall 2024.
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