BREAKING: Your Body Burns More Calories Than We Thought — Dr. Howard on the Groundbreaking Study Rewriting Metabolism

Optimal Protein Podcast with Vanessa Spina

Vanessa Spina

Fitness, Health & Fitness, Nutrition

4.5 • 758 Ratings

🗓️ 8 December 2025

⏱️ 72 minutes

🔗️ Recording | iTunes | RSS

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Summary

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In today's episode, Vanessa sits down with Dr. Howard, the lead author of a brand-new PNAS study that is challenging one of the most widely accepted ideas in human metabolism.

For years, many scientists believed that our bodies operate within a fixed daily calorie "budget," and that after a certain point, increasing activity doesn't increase total calorie burn. But Dr. Howard's new research suggests the story may be far more dynamic — and far more empowering — than we ever realized.

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This conversation explores what this new evidence could mean for:

How we think about calorie burn
Why activity matters (in ways we didn't fully understand before)
The role of fueling, recovery, and energy balance
What actually drives fat loss and body recomposition
How to train smarter, not harder

Mentioned in this episode:

Physical activity is directly associated with total energy expenditure without evidence of constraint or compensation — published in Proceedings of the National Academy of Sciences (PNAS).

Read the full study here → PNAS DOI 10.1073/pnas.2519626122

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The content provided in this podcast is for informational purposes only and should not be construed as medical advice. Consult with a healthcare professional before making significant changes to your diet or exercise regimen.

Transcript

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0:00.0	Welcome to the optimal protein podcast. I'm Vanessa Spina.
0:04.8	Hello, my friends. Welcome back to the optimal protein podcast. I'm your host, Vanessa, and I am so
0:10.3	excited about today's episode because we are diving into a groundbreaking new study with the study
0:18.3	author herself. And this study may completely change the way that we think
0:23.7	about human metabolism, energy expenditure, exercise, and fat loss. Now, for nearly a decade,
0:32.4	this space has really been shaped by something known as the constrained energy model proposed by Dr. Herman
0:40.2	Ponser. And the idea was that our bodies operate within a fixed daily calorie budget.
0:46.8	Now, according to that model, once we cross roughly 800 active calories per day, our total daily energy expenditure plateaus. And the body begins
0:58.2	downregulating other systems like digestion, immunity, or even thyroid function to compensate.
1:06.6	Now, this theory profoundly influenced how many people around the world, myself included, thought
1:12.4	about exercise, calorie burn, and metabolism. It has shaped conversations around why we can't
1:18.9	out exercise our diet and why calorie burn alone is not the best predictor of fat loss
1:25.3	and why exercise sometimes feels less effective than it should.
1:30.3	Now, our guest today is Dr. Howard, and she has completely upended that narrative with a brand new
1:36.7	study. This was just published in Pinas in 2025, and her research uses the gold standard method of doubly labeled water, which we
1:47.4	explain in detail what that is in the episode today, to measure true energy expenditure in
1:52.8	adults ranging from sedentary individuals to people running six or more miles today.
1:57.4	Now, her findings were actually groundbreaking and quite counter to what Dr.
2:04.8	Herman Ponser proposed. Now, the difference is that her research was done in weight stable individuals,
2:11.8	whereas Dr. Ponzer's research was not. Now, this new research suggests that our bodies don't necessarily start
2:20.1	compensating or plateauing once we reach 800 active calories per day. And actually, as long as we
2:28.3	stay fueled, our calorie burn can continue to increase. Now, this is absolutely fascinating research,
	...

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