Sigma Nutrition Radio

• #581: What Is Successful Public Nutrition Policy? And Why Is It So Hard to Achieve? – Emily Callahan, RD, MPH

  Public nutrition policy plays a critical role in shaping population health through laws, guidelines, and programs that influence what people eat. In this episode, Emily Callahan, an expert in nutrition policy, talks about why public nutrition policies often fall short and what “success” looks like. They discuss how evidence-based nutrition interventions can stall due to political or practical barriers, and explore examples ranging from federal food assistance programs to sodium reduction initiatives. Crucially, they address how to evaluate if a policy has worked and highlight emerging strategies (like integrating “food as medicine” into healthcare) that offer hope for better outcomes. This conversation is highly relevant for researchers, clinicians, and nutrition professionals, as it underscores the importance of policy in addressing nutrition challenges at the population level and examines how to design effective, data-driven policies for public health impact. Timestamps [05:09] Understanding public health nutrition policy [08:44] Examples of public nutrition policies [21:27] Challenges in implementing nutrition policies [31:24] Evaluating the success of nutrition policies [34:58] Sustainability and political viability of health policies [38:07] Food Is Medicine: a promising policy target [44:50] Medically tailored meals: evidence and implementation [48:55] The MAHA commission report and its implications [56:42] Future directions in nutrition policy [01:04:49] Key ideas segment (premium-only) Related Resources Join the Sigma email newsletter for free Subscribe to Sigma Nutrition Premium Go to episode page Enroll in the next cohort of our Applied Nutrition Literacy course JAMA Commentary: The MAHA Commission Report and Diet-Related Diseases in Youth – Mozaffarian, Callahan & Frist, 2025 Mozafarrian et al., 2024 – “Food Is Medicine” Strategies for Nutrition Security and Cardiometabolic Health Equity: JACC State-of-the-Art Review Tufts’ Food Is Medicine Institute

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• #580: Sodium Bicarbonate for Sports Performance – Prof. Lewis Gough

  Sodium bicarbonate is one of the most consistently supported ergogenic aids in sports nutrition research, yet its underlying mechanisms and real-world applications remain widely misunderstood. More recent developments have focused on how to optimise both the timing and formulation of supplementation. The “individualised ingestion timing” approach has emerged as a practical strategy, recognising that the time-to-peak blood bicarbonate concentration varies considerably between individuals. Similarly, novel formulations are being explored to address issues with gastrointestinal distress and practicality of dosing. These include topical approaches such as sodium bicarbonate lotion, and commercial products like Maurten’s “Bicarb System.” In this episode, Prof. Lewis Gough joins to discuss the latest evidence on sodium bicarbonate and performance, its mechanisms, novel delivery systems, and the key directions for future research. Dr. Lewis Gough is a Professor of Nutrition and Physiology at Birmingham City University. He is globally recognized for his research on sodium bicarbonate supplementation in sport, and his work spans applied sport and exercise nutrition, exercise metabolism, acid–base balance, and fatigue. Timestamps [03:12] Professor Gough’s academic journey [06:29] Mechanisms of sodium bicarbonate and historical perspective on lactate [11:21] Sodium bicarbonate’s role in performance [22:45] Individual responses to sodium bicarbonate [26:53] Timing strategies for sodium bicarbonate [32:38] Individualized approach to sodium bicarbonate timing [36:47] Traditional vs. novel delivery methods [44:27] Practical recommendations for athletes [51:18] Future research directions [01:02:08] Key Ideas segment Resources Go to episode page (w/ links to relevant studies) Subscribe to Sigma Nutrition Premium Join the Sigma email newsletter for free Enroll in the next cohort of our Applied Nutrition Literacy course See all of Sigma's "Recommended Resources"

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• #579: Is Your Chronotype Hard-Wired or Modifiable? And What Does It Mean for Health?

  In this episode, we explore the concept of chronotype, which reflects an individual’s biological circadian timing and how it manifests in preferred sleep–wake patterns. Understanding chronotype is important because it differs from simple diurnal preference, which may be shaped by lifestyle or psychological factors rather than biology. We examine how chronotype is measured, from gold-standard laboratory methods to validated questionnaires used in field studies. The discussion also highlights the importance of accounting for sleep debt when estimating true biological timing. Finally, we consider the limitations of consumer devices and the practical implications of assessing chronotype in real-world settings. Timestamps [02:02] Understanding chronotypes [06:26] Measuring chronotypes [15:12] Genetic and environmental influences on chronotypes [28:34] Health implications of chronotypes [52:21] Practical applications Related Resources Join the Sigma email newsletter for free Subscribe to Sigma Nutrition Premium Become a member of Alan Flanagan’s Alinea Nutrition Education Hub Enroll in the next cohort of our Applied Nutrition Literacy course Related previous episodes: 495, 470, 469

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• #578: Creatine For Brain Health: Overhyped Trend or Science-based Intervention? – Prof. Eric Rawson

  Creatine is best known as a sports supplement for enhancing muscle strength and high-intensity performance. But could it also improve brain health and cognitive function? Or are such claims overhyped? If creatine can support brain health, it could have implications for aging, neurodegenerative diseases, concussion recovery, and mental fatigue. In this podcast episode, Professor Eric Rawson discusses what current science says about creatine’s effects on the brain, including memory, executive function, and protection against neurological stress. Professor Rawson provides context on how creatine works in the body, why the brain might benefit, and what evidence exists so far. Eric Rawson, PhD is Professor and Chair in the Department of Health, Nutrition & Exercise Science at Messiah University. For over twenty years, his research has centered on the interplay between nutrition and skeletal muscle, notably investigating how creatine supplementation affects both muscle and brain function. Timestamps [03:14] Understanding creatine: biochemistry and history [07:55] Creatine supplementation and muscle performance [09:35] Creatine and brain health: emerging research [14:03] Measuring brain creatine: challenges and techniques [19:58] Cognitive benefits of creatine supplementation [26:23] Evaluating the evidence: caution and promise [30:45] Mega dosing and brain health protocols [32:04] Creatine for brain health: context matters [38:54] Creatine for brain injury and aging [51:25] Key ideas segment (Premium-only) Related Resources Join the Sigma email newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Links to related studies (see Related Resources section)

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• Is There a Limit to Energy Expenditure? And What Happens When We Push It? (SNP44)

  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. Timestamps [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 Resources Subscribe to Premium Go to sigmanutrition.com 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

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