Podcast Summary: The Dr. Shannon Show (#222): UPDATED SCIENCE: How We Burn Calories
Date: November 13, 2025
Host: Dr. Shannon Ritchey, PT, DPT

Episode Overview

In this solo episode, Dr. Shannon Ritchey dives deep into the evolving science of calorie burning, challenging widely-held beliefs about how our bodies expend energy during exercise and daily activity. She juxtaposes her previous stance—rooted in the concept of "constrained" calorie expenditure—with new research suggesting an "additive" model. The episode explores how these insights impact approaches to fitness, nutrition, and mental well-being, particularly for those interested in body recomposition.

Key Discussion Points & Insights

1. The Importance of Staying Evidence-Based

• Dr. Shannon opens with personal reflections, emphasizing her commitment to updating her audience as new research emerges:
  • "One thing that is extremely important to me is staying as evidence based as possible. This industry can be extremely dogmatic." (03:55)
• She criticizes thought leaders who ignore new evidence and double down on old views.

2. The Old Theory: Constrained Energy Expenditure ([06:24])

• Based on Herman Pontzer’s study of 300+ individuals, the constrained model suggests:
  • As activity increases, total daily energy expenditure plateaus.
  • The body "borrows" calories from other systems like digestion, reproduction, or immunity.
  • Plateau observed around 800 active calories/day.
• Personal application: Dr. Shannon describes how this data changed her relationship with exercise and nutrition:
  • "I stopped optimizing for calorie burn and started optimizing for the stimulus to build muscle... For the first time in my life, I started separating food from exercise." (10:02)
• Mental health benefit: Shifting focus away from "earning" or "erasing" food via exercise.

3. The New Study: Additive Calorie Expenditure ([13:02])

• In October 2025, Howard and colleagues published a study with 75 weight-stable US adults—ranging from sedentary to running 6+ miles/day.
• Key findings:
  1. Energy expenditure increased linearly with activity (no plateau).
  2. No signs of other systems downregulating (checked via immune, reproductive, thyroid biomarkers).
  3. No evidence of caloric "borrowing" from other body systems.
  • "To my initial disappointment, and quite frankly, confusion, the results of this study directly contradicted Pontzer's findings." (14:19)

4. Reconciling the Two Theories ([17:10])

• Dr. Shannon analyzes methodological differences:
  • Pontzer: Diverse, not all weight-stable; some in deficit/surplus.
  • Howard: Only weight-stable individuals.
  • "If you're in a deficit, your body has less available energy. So compensation or down regulation... is more likely. If you're fueling to replace the calories you burned, you might be able to increase your calorie burn linearly." (17:47)
• Conclusion: Both models may be correct, depending on context (deficit vs. maintenance; low vs. high activity).

5. Practical Recommendations for Listeners ([19:27])

• For Most People (Moderate Activity, Eating Enough):
  • Calorie burn appears mostly additive.
  • Muscle-building (near-failure lifts) remains key for body recomposition.
  • 150 minutes/week of light to moderate cardio (Dr. Shannon prefers walking).
• For Fat Loss:
  • Diet still primary.
    • "You simply can't outrun your fork, even if calorie burn is more additive than we thought." (20:08)
• Should You Add More Activity?
  • Only if recovery isn't compromised.
  • Over-exercising undermines performance and body composition goals.

6. Why Dr. Shannon is No Longer Using the "800 Active Calories" Benchmark ([22:40])

• She will stop referencing specific "active calorie" targets.
• Continues to discourage tracking calories burned during workouts for these reasons:
  1. Strength workouts are about muscle-building, not high calorie burn.
  2. Fitness trackers are highly inaccurate.
  3. Fixation on calorie burn is detrimental for mental health. - "When you optimize for calorie burn, we stop using exercise for health and start using it for punishment." (23:55)

7. Paradigm Shift: Exercise as a Stimulus, Not a Calorie Eraser ([24:42])

• Overall takeaway:
  • "When you shift your focus from exercise as burning towards exercise as a stimulus for building, you'll see the results you're looking for, feel so much better physically, and get the mental relief from the never enough mentality that plagues so many of us."

Notable Quotes & Moments

• On updating her stance:

  • "Doubling down on antiquated beliefs is exactly how we stay stuck and don't change or improve. And the reality is that science is continually evolving." (02:38)

• On separating food from exercise:

  • "I started taking more responsibility for my nutrition... I never tell myself I'll just eat whatever I want because I can go burn it off later." (09:41)

• On the significance of new research:

  • "Calorie burned appeared additive, not constrained, at least under the conditions they studied." (15:40)

• On practical advice:

  • "Overdoing it with a lot of exercise will run you down and make your workouts less effective... you're adding more but getting less." (21:40)

Timestamps for Major Segments

• 01:25—Personal/family update, podcast process motivation
• 03:55—Commitment to evidence-based science and criticism of dogma
• 06:24—Explanation of constrained energy model (Pontzer’s research)
• 10:02—Impact of the constrained model on Dr. Shannon’s philosophy and life
• 13:02—Introduction of new "additive" burn study by Howard et al.
• 14:19—Details of Howard’s findings and direct contrast with older research
• 17:10—Reconciliation of the two theories; context matters
• 19:27—Practical recommendations for exercise and diet
• 22:40—Why she’s dropping the 800 calorie number and advice against tracking burned calories
• 24:42—Final word: Shift to exercise as building, not burning

Conclusion and Takeaway

This episode marks a significant shift in Dr. Shannon Ritchey’s recommendations on calorie expenditure:

• She now recognizes that, for most people who eat at maintenance and exercise moderately, calorie burn is likely additive—not capped as previously believed.
• Her revised advice centers on optimizing for muscle-building, maintaining enjoyable and sustainable activity levels, focusing on nutrition for fat loss, and preserving mental resilience by avoiding obsession over calorie trackers or the pursuit of burning off food through exercise.

Listeners are encouraged to train smarter, not harder, and to keep an open, evidence-driven approach as new science emerges.