Energy expenditure is one of the most fundamental yet often misunderstood aspects of human physiology. A central question is whether there is a ceiling to how many calories we can burn, and what happens when activity levels approach that limit. Grasping these dynamics is essential for health professionals and researchers, as energy balance directly influences body weight regulation, metabolic health, and athletic performance.

Emerging research shows that our bodies regulate calorie burn not in a fixed manner, but through adaptation and compensation, revealing that the “calories in vs. calories out” model is far more dynamic than it may first appear.

In this episode, we revisit key insights from experts such as Dr. Herman Pontzer, Dr. Brent Ruby, Dr. Mark Hopkins, Dr. Eric Trexler, and Dr. Chris Melby. These perspectives cover how the body adapts to different levels of physical activity, the metabolic adjustments during weight loss (often called adaptive thermogenesis), and the concept of energy flux in weight maintenance.

Note: This episode is one of our Premium-exclusive episodes. To listen to the full episode, you’ll need to be a Premium subscriber and access the episode on the private Premium feed. Otherwise, you can hear a preview of the episode on the public feed of the podcast.

• [03:36] Contrained model of energy expendiure
• [12:33] What is the ceiling of human energy expenditure?
• [13:05] Reconciling energy intake and expenditure
• [13:32] Variability in metabolic rates
• [15:16] Adaptive thermogenesis and weight loss
• [18:37] Metabolic adaptation explained
• [31:51] Energy flux and weight maintenance

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• Article: The “Calories In, Calories Out” Confusion: A Comprehensive Guide to Understanding Energy Balance
• Included episodes:
  • 208 – Herman Pontzer, PhD | Constrained Energy Expenditure Model & Evolutionary Biology of Energy Balance
  • 124 – Brent Ruby, PhD | The Human Ceiling of Energy Expenditure
  • 299 – Mark Hopkins, PhD | Compensatory Eating & Activity Energy Expenditure
  • 377 – Herman Pontzer, PhD | Metabolism, Mitochondria & Measuring Energy Expenditure
  • 484 – Eric Trexler, PhD | Is Metabolic Adaptation an Illusion?
  • 318 – Chris Melby, DrPH | Impact of Energy Flux on Weight Management

Recently a new trial was published in Nature Medicine comparing the effect of ultra-processed versus minimally processed diets. Specifically, the UPDATE trial compared these two diets in the context of a healthy dietary pattern (in line with the UK’s EatWell Guide).

This eight-week randomized, crossover trial generated a lot of discussion and was largely seen as being a really useful addition to the evidence base, and providing answers to some previously unexamined questions.

In this episode the study’s lead author, Dr. Samuel Dicken, explains the background context for the UPDATE trial, provides an insight into its execution, and puts some of the results in context. There is also a discussion about the current state of evidence more broadly and the leading hypotheses around the mechanisms that drive the observations seen with consuming ultra-processed foods.

This episode is particularly noteworthy because it provides fresh evidence on an important question: does following dietary guidelines with minimally processed foods confer extra benefits over following the same guidelines with ultra-processed foods?

• [02:48] Interview with Dr. Samuel Dicken
• [03:08] Background and research interests of Dr. Samuel Dicken
• [04:31] Details of the update trial
• [09:48] Trial design and methodology
• [15:45] Results and findings of the update trial
• [18:46] Secondary outcomes and craving control
• [25:43] Hypotheses and mechanisms behind UPF effects
• [40:28] Policy implications and future research directions

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• Study: Dicken et al., 2025 – Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial
• LinkedIn: Samuel Dicken
• X: @SamuelDickenUK

In this episode, Dr. Matthew Facciani explores how social psychology influences health beliefs and the spread of misinformation. The conversation delves into why people adopt certain nutrition or health beliefs so strongly, how identity and group membership shape our interpretation of evidence, and what makes us susceptible to false or misleading health claims.

Dr. Facciani’s interdisciplinary background (spanning neuroscience, psychology, and sociology) allows him to offer a unique evidence-informed perspective on these issues. The episode centers on understanding the social forces behind health-related attitudes and how we might improve communication and critical thinking in the face of rampant misinformation.

This topic is highly relevant for health professionals and researchers because misinformation about nutrition, health, and medicine can lead to poor decisions, vaccine hesitancy, or harmful fad diets. By understanding the psychological drivers that cause people to cling to unscientific beliefs, practitioners can better address patients’ concerns and correct false claims.

Matthew Facciani is a postdoctoral researcher at The University of Notre Dame in the Computer Science and Engineering Department. He is an interdisciplinary social scientist with a background in neuroscience and psychology and holds a PhD in sociology. His research focuses on media literacy, misinformation, social networks, political polarization, identities, and artificial intelligence.

• [01:41] Interview start
• [06:57] The role of identities in belief formation
• [16:01] Health attitudes and political identities
• [25:28] Improving dialogue and addressing misinformation
• [31:59] Does fact-checking work?
• [35:41] Media literacy and pre-bunking
• [44:03] Optimism and pessimism for the future
• [52:28] Key ideas segment (premium-only)

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• Enroll in the next cohort of our Applied Nutrition Literacy course
• Matthew’s book: ‘Misguided’
• Matthew’s academic publications
• Recommended episode: #365: David Robert Grimes, PhD – Conspiracy Theories & Bad Information: Why Are We Susceptible?