Sigma Nutrition Radio

This is a Premium-exclusive episode of the podcast. To listen to the full episode you need to be subscribed to Sigma Nutrition Premium. Each year, the conversations on Sigma Nutrition Radio aim to examine the ideas that shape how we understand nutrition, health, and human behavior. This episode brings together the key insights from those discussions, revisiting the most important themes, emerging evidence, and shifts in understanding from the past year. Across topics such as dietary guidelines, ultra-processed foods, sleep, metabolism, environmental exposures, and the psychology of eating, this review distills what the science actually shows and what remains uncertain. Whether you have followed throughout the year or are tuning in for the first time, this episode provides a concise synthesis of what truly mattered and what these ideas imply for how we interpret nutrition science moving forward. Timestamps [02:23] Christopher Gardner, PhD[13:10] Marie-Pierre St-Onge, PhD[20:03] Duane Mellor, PhD[29:26] Samuel Dicken, PhD[35:37] Ian Mudway, PhD[43:46] Martin Caraher, PhD Related Resources the episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition Literacy

We take a look at critical thinking in science and healthcare, examining how we often fall prey to cognitive biases, emotional reasoning, and flawed thinking. Drawing from six different experts in their respective fields, the episode explores why we sometimes believe we are being rational when in fact our conclusions aren't truly evidence-based. The discussion spans what genuine evidence-based practice means, how domain expertise matters, and how factors like identity, beliefs, and emotions can derail objective reasoning. Timestamps [02:56][15:30][26:10][30:10][37:18][42:31] Related Resources episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition LiteracyAlinea Nutrition Education Hub

How should we think about diets that claim to optimise both human and planetary health? Can a single "reference diet" really balance the complex trade-offs between nutrition adequacy, chronic disease prevention, and environmental sustainability? These questions have gained renewed attention with the release of the 2025 update to the EAT-Lancet Planetary Health Diet. The original 2019 report proposed a mostly plant-based dietary pattern designed to improve population health while staying within planetary boundaries. But since then, new data have emerged—on nutrient requirements, disease risk, and environmental modelling—that complicate many of the original assumptions. What does the updated evidence actually say about the health impacts of eating in line with this framework? How have the environmental projections changed? And what do these evolving targets mean for individuals, policymakers, and researchers trying to translate broad sustainability goals into practical dietary guidance? These are some of the questions explored in this episode of Sigma Nutrition, which examines the 2025 EAT-Lancet update, its scientific foundations, and what it reveals about the intersection of nutrition, health, and planetary sustainability. Timestamps [01:46][02:27][03:13][03:40][04:14][09:12][27:00][40:01][44:13][49:48][58:55]Premium-only Links & Resources episode page (with links to studies)Sigma email newsletterSigma Nutrition Premium Alinea Nutrition Education HubApplied Nutrition LiteracyEAT-Lancet

Ultra-processed foods have become central to the way we eat and to many of the challenges we face in public health nutrition. They dominate supermarket shelves, shape population diets, and often appear as the prime suspect in rising obesity and metabolic disease rates. But beyond the label itself, what exactly makes these foods problematic? Is it their nutrient composition, their texture and palatability, the rate at which we consume them, or the broader environments that make them so accessible and appealing? The debate around ultra-processed foods sits at the intersection of metabolic science, behaviour, and policy. It raises uncomfortable questions about how food systems evolved to prioritise convenience and profit, and what it might take to meaningfully change that trajectory. In this episode, Dr. Kevin Hall joins the podcast to examine the evidence from controlled feeding studies and population research, exploring what we really know about ultra-processed foods, overeating, and how we might begin to fix the food environment. Timestamps [04:24][06:47][15:10][27:00][30:43][33:03][44:26][49:10][51:50] Links & Resources episode page (with links to studies)Sigma email newsletterSigma Nutrition PremiumApplied Nutrition Literacy@KevinH_PhD@NutritionDannyFood Intelligence: The Science of How Food Both Nourishes and Harms Us

This is a Premium-exclusive episode of the podcast. To listen to the full episode you need to be subscribed to Sigma Nutrition Premium. What exactly are "antioxidants," and why do they get so much hype? We often hear that blueberries, dark chocolate, and red wine are healthy because they're packed with antioxidants – but is the story really as simple as "more antioxidants = better health"? In this episode, Danny explores the true role of antioxidants in the body, challenging simplistic narratives. Are antioxidants magic molecules that single-handedly prevent aging and disease? Or is the reality more nuanced, with context and balance being key? We delve into these intriguing questions to clarify what antioxidants are, how they work, and what the current consensus tells us about using them for health. Antioxidants are frequently credited as the reason why colorful fruits and vegetables are beneficial. Yet, as past Sigma episodes on polyphenols have noted, the benefits of those plant foods aren't primarily due to direct antioxidant effects. Here we untangle common misconceptions (e.g., "antioxidants = health, always"), distinguish between different types of antioxidants, and explain why simply taking high-dose antioxidant supplements isn't a guarantee of protection – and in some cases might even backfire. By the end, health professionals and science-savvy listeners will understand the diverse roles of antioxidants, the importance of balance, and how to apply this knowledge in practice. Timestamps [01:27][04:19][08:43][09:58][16:03][24:28][27:39][36:47] Links & Resources: Sigma Nutrition Premiumepisode pageSigma email newsletterAlinea Nutrition Education HubApplied Nutrition LiteracyRecommended Resources@sigmanutrition@NutritionDanny

GLP-1 receptor agonists have emerged as a groundbreaking tool in obesity treatment. In this episode, Dr. Spencer Nadolsky (an obesity specialist) explains how these medications are now yielding unprecedented weight loss outcomes in people with obesity. The discussion centers on GLP-1 agonist drugs like semaglutide and tirzepatide: how they work, how much weight loss they can produce, and why they represent a paradigm shift in obesity management. Importantly, the conversation addresses practical aspects of using these drugs, including managing their side effects and optimizing patients’ diet and lifestyle while on therapy. This topic is of great significance to nutrition science, clinical practice, and public health. Obesity is a chronic, relapsing condition that has proven difficult to treat with lifestyle changes alone. The advent of GLP-1 agonists offers new hope by inducing weight loss levels previously seen only with surgical interventions. Understanding these medications is crucial for healthcare professionals: it enables evidence-based prescribing, proper patient counseling on diet and side effects, and integration of medication with lifestyle interventions. Discussing safety and long-term use is vital, as millions more patients might use these drugs in coming years. From a public health perspective, GLP-1 agonists prompt debates about access and cost, given their high price and life-changing potential. Timestamps [03:25][05:24][07:55][16:53][22:57][28:09][29:38][33:48][36:59][43:25][46:16] Related Resources episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition LiteracyVineyard – Dr. Nadolsky’s Virtual Clinic (US)@drnadolsky@sigmanutrition460: Dr. Priya Sumithran – Body Fat Regulation, Pros & Cons of Weight Loss Interventions, and GLP-1 Receptor Agonists324: Fatima Cody Stanford, MD – Obesity Treatment & Weight Bias395: Prof. Carel Le Roux – Current Thinking in Obesity Treatment

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][08:44][21:27][31:24][34:58][38:07][44:50][48:55][56:42][01:04:49] Related Resources Sigma email newsletterSigma Nutrition Premiumepisode pageApplied Nutrition LiteracyThe MAHA Commission Report and Diet-Related Diseases in Youth – Mozaffarian, Callahan & Frist, 2025Mozafarrian et al., 2024 – “Food Is Medicine” Strategies for Nutrition Security and Cardiometabolic Health Equity: JACC State-of-the-Art ReviewTufts’ Food Is Medicine Institute

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 Associate Professor in 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][06:29][11:21][22:45][26:53][32:38][36:47][44:27][51:18][01:02:08] Resources episode pageSigma Nutrition PremiumSigma email newsletterApplied Nutrition Literacy"Recommended Resources"

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][06:26][15:12][28:34][52:21] Related Resources Sigma email newsletterSigma Nutrition PremiumAlinea Nutrition Education HubApplied Nutrition Literacy

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][07:55][09:35][14:03][19:58][26:23][30:45][32:04][38:54][51:25](Premium-only) Related Resources Sigma email newsletterSigma Nutrition PremiumApplied Nutrition LiteracyLinks to related studies

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][12:33][13:05][13:32][15:16][18:37][31:51] Resources Subscribe to Premiumsigmanutrition.comThe “Calories In, Calories Out” Confusion: A Comprehensive Guide to Understanding Energy Balance

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? Timestamps [02:48][03:08][04:31][09:48][15:45][18:46][25:43][40:28] Related Resources Sigma Nutrition Premiumepisode pageSigma email newsletterApplied Nutrition LiteracyDicken et al., 2025 – Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trialSamuel Dicken@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. Timestamps [01:41][06:57][16:01][25:28][31:59][35:41][44:03][52:28] Related Resources episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition Literacy‘Misguided’academic publications#365: David Robert Grimes, PhD – Conspiracy Theories & Bad Information: Why Are We Susceptible?

Dairy is often treated as a single food group, yet milk, yogurt, cheese, and butter can have very different effects on health. Some evidence links yogurt to favourable outcomes, while butter is known to raise LDL cholesterol. And then there’s the paradox of cheese: high in saturated fat, but not consistently associated with higher heart disease risk. These complexities raise the question of whether the “dairy matrix” (the combination of nutrients and food structure) explains why not all dairy acts the same. In this episode, Prof. Jean-Philippe Drouin-Chartier, a nutrition researcher and registered dietitian, is on the show to examine what recent trials and large population studies tell us about dairy foods and cardiometabolic health. The discussion covers blood lipids, blood pressure, glucose metabolism, and how guidelines should interpret this evolving evidence. Timestamps [02:18][09:38][16:06][21:42][25:56][43:30] Related Resources Sigma Nutrition PremiumSigma email newslettersigmanutrition.comApplied Nutrition Literacylinked here

They’re in our oceans, our air, our food, and now even in our bodies. Microplastics, once a distant environmental issue, have become a topic of urgent relevance in medicine, public health, and nutrition. The idea that tiny plastic particles are circulating through the food chain and accumulating in human tissues has sparked headlines, speculation, and concern. But how much of this fear is grounded in solid science? And how much is still unknown? As the research into microplastics rapidly grows, so too does the confusion. Claims range from the plausible to the alarmist, yet the real picture is far more complex. What does current evidence actually tell us about the health implications of microplastic exposure? How do we weigh these emerging signals against the backdrop of other environmental threats we understand much better? And how should scientifically-minded practitioners think about this issue, especially when patients begin asking questions? This is a conversation that calls for clarity, nuance, and a rigorous look at what we know versus what remains speculative. In this episode, Professor Ian Mudway, an environmental toxicologist, discusses the current scientific understanding of microplastics and human health. Timestamps [03:31][08:35][11:35][14:54][18:23][21:38][27:08][29:53][33:08][40:34][48:09] Resources Sigma Nutrition PremiumSigma email newsletterApplied Nutrition Literacy Gresham College YouTube lecturessigmanutrition.com

In this episode, performance nutritionist Daniel Davey discusses how his approach to elite sports nutrition has evolved over his career. Davey reflects on his decade working with top Irish teams (Dublin GAA/football and Leinster Rugby) and how stepping away from those environments led him to rethink the role of a nutrition practitioner. The central theme is a shift from a traditional prescriptive model, where the expert provides meal plans and quick solutions, to a philosophy centered on athlete empowerment, education, and long-term habit development. Davey emphasizes that true high performance is achieved not by spoon-feeding athletes every nutrient, but by cultivating their independence, adaptability, and ownership of the process. This episode delves into practical strategies for fostering that ownership, such as encouraging self-reflection, building a supportive “nutrition culture,” and focusing on sustainable habits over short-term fixes. This discussion is highly relevant to nutrition science and clinical practice because it addresses the often-overlooked behavioral and cultural aspects of dietary change. Health professionals will recognize parallels to coaching clients in any setting: the importance of engaging individuals in their own nutrition planning, the value of reflective practice, and the balance between providing support and encouraging autonomy. Timestamps [02:38][07:29][12:36][16:53][23:33][28:00][30:03][31:47][34:38][40:27][52:31] Resources Sigma email newsletterSigma Nutrition PremiumApplied Nutrition LiteracyRecommended Resources

Nutrition science plays a pivotal role in shaping public health advice, but the influence of industry funding on research has become a pressing concern. In this episode we want to examine whether we can trust nutrition studies funded by food and beverage companies, and how you can discern study credibility. The discussion is highly relevant in today’s landscape, where conflicts of interest and bias in research are under scrutiny amidst debates on sugar, processed foods, and diet recommendations. By exploring how industry sponsorship might skew results or interpretations, this episode speaks to broader issues of scientific trustworthiness and evidence-based policy in nutrition and public health. In this episode, we take a look at some recent publications that showed how study results and reporting differed significantly depending on if industry had funded the study or not. We delve into how this happens. As most often it is not a case of data fabrication or corruption, but rather how bias leads to studies being designed and reported differently. We walk through some examples, as well as highlighting some industry-funded studies that didn’t provide a “pro-industry” result and conclusion. The hope is that the episode allows you to understand why this is a problem, how to spot it, and how to know if you can trust the results of an industry-funded study. Timestamps [00:36][04:47][15:06][30:43][36:37][38:06][51:58][01:01:51][01:07:14] Related Resources Sigma email newsletterSigma Nutrition PremiumAlinea Nutrition Research HubApplied Nutrition Literacy#472: Compared To What? – Understanding Food Substitution Analysis & Adjustment ModelsLópez-Moreno et al., Am J Clin Nutr. 2025 Jun;121(6):1246-1257You are what you don’t eatMandrioli D, Kearns CE, Bero LA (2016) PLOS ONE 15(3): e0230469Schillinger et al., Ann Intern Med. 2016 Nov 1;165(12):895–897Schmidt et al., 2021 – The impact of diets rich in low-fat or\ full-fat dairy on glucose tolerance and its determinants: a randomized controlled trialSchmidt et al., 2021 – Impact of low-fat and full-fat dairy foods on fasting lipid profile and blood pressure: exploratory endpoints of a randomized controlled trial

In recent years “Zone 2 training” has gained immense popularity in fitness and health circles, often being proclaimed the “best” cardiovascular training for metabolic health. Zone 2 training is sustained, low-intensity exercise below the lactate threshold that is commonly employed by many elite level endurance athletes, with a variety of proposed performance benefits. This led to interest from health-conscious folks about its ability to improve markers like VO2 max and mitochondrial function, which are associated with better health outcomes and longevity. Prof. Brendon Gurd, an exercise physiologist at Queen’s University, is the co-author of a recent review published in Sports Medicine that examined some of the claims made around zone 2 training and health in the general population. This episode looks at whether the evidence truly supports Zone 2 as a uniquely effective training zone or if this hype has outpaced the research. These insights help professionals and individuals make evidence-based recommendations and avoid unintended negative consequences of following certain ideas. About The Guest Dr. Brendon Gurd is a Professor in the School of Kinesiology and Health Studies at Queen’s University, where his research focuses on exercise physiology and skeletal muscle adaptation. His work explores how different intensities and types of exercise influence mitochondrial content and function in muscle tissue, with the goal of understanding how to optimize health and performance through training. Timestamps [03:23][05:56][10:56][22:16][35:47] Links to Resources Sigma Nutrition PremiumSigma email newsletterApplied Nutrition LiteracyRecommended ResourcesStoroschuk et al., 2025 – Much Ado About Zone 2: A Narrative Review Assessing the Efficacy of Zone 2 Training for Improving Mitochondrial Capacity and Cardiorespiratory Fitness in the General PopulationProf. Brendon Gurd – Is Zone 2 the optimal intensity for inducing mitochondrial adaptation?

Fructose has often been labeled a uniquely damaging nutrient, blamed for obesity, diabetes, and other metabolic diseases. But does fructose truly have unique harmful effects or are the risks associated with it related to context and quantity? The episode explores how fructose is metabolized in the body, why it gained a reputation for being problematic, and what the scientific evidence says about fructose in our diets. You will gain insight into why fructose was singled out in the past (e.g., its unique pathway in the liver and lack of insulin response), and how newer studies put those concerns into context. It covers important nuances for practitioners and health-conscious individuals, especially given public confusion and fear around fructose (even in fruit). Guest Information Dr. Scott Harding, Ph.D., is an Associate Professor of Nutritional Biochemistry in the Department of Biochemistry at Memorial University of Newfoundland. His research explores the complex interactions between diet, metabolism, and chronic disease, with a particular emphasis on the metabolic effects of dietary sugars (especially fructose), the role of fats and phytosterols in lipid metabolism, and how public health policies like sugar taxation influence population health outcomes. Timestamps [02:58][08:45][12:51][23:07][29:53][31:12][40:58][45:10][54:06] Related Resources Sigma Nutrition PremiumSigma email newsletterApplied Nutrition Literacy"Recommended Resources"

Vitamin A is often one of the less-discussed micronutrients in relation to bone health, taking a back seat to nutrients like calcium and vitamin D. Yet this fat-soluble vitamin plays a fundamental role in skeletal development, remodeling, and mineral homeostasis. It influences gene expression in both osteoblasts and osteoclasts, and contributes to the regulation of bone turnover throughout the lifespan. But what makes vitamin A particularly interesting, and controversial, is that its effects on bone appear to follow a double-edged pattern. While it’s essential for bone formation, several large epidemiological studies have suggested that chronically high intakes of preformed vitamin A may actually increase the risk of osteoporosis and fracture, especially when consumed as retinol from supplements or high-liver diets. And yet, the picture is not so clear-cut. This raises compelling questions: In this episode, we explore the human evidence on vitamin A and skeletal health, looking not only at fracture outcomes and bone mineral density data, but also at nutrient interactions, mechanistic plausibility, and the implications for supplement use in well-nourished populations. Note: This is a Premium-exclusive episode, so you will only hear a preview on this public feed. Timestamps [00:23][02:50][04:16][17:52][31:03] Related Resources Sigma Nutrition PremiumSigma email newsletterSigma Nutrition.comApplied Nutrition Literacy