Explorez tous les épisodes du podcast Sigma Nutrition Radio
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| #625: Does Changing the Microbiome Actually Improve Health? – Prof. Harry Sokol | 27 oct. 2026 | 00:46:02 | |
Claims about "improving the gut microbiome" are widespread, but what would improvement actually mean? How do we establish which microbial changes contribute to disease, and which simply reflect it? Research on bacterial metabolism of medications raises questions about how the microbiome might influence treatment efficacy and toxicity. What would it take to translate these findings into reliable tests and effective therapies? In this episode, gastroenterologist and researcher Prof. Harry Sokol examines these questions, discusses the development of Faecalibacterium prausnitzii as an investigational treatment, and considers what current evidence can tell us about dietary advice and commercial microbiome testing. Timestamps
Claims about "improving the gut microbiome" are widespread, but what would improvement actually mean? How do we establish which microbial changes contribute to disease, and which simply reflect it? Research on bacterial metabolism of medications raises questions about how the microbiome might influence treatment efficacy and toxicity. What would it take to translate these findings into reliable tests and effective therapies? In this episode, gastroenterologist and researcher Prof. Harry Sokol examines these questions, discusses the development of Faecalibacterium prausnitzii as an investigational treatment, and considers what current evidence can tell us about dietary advice and commercial microbiome testing. Timestamps
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| #624: Can Athletes Eat for Performance and the Planet? – Peter Res | 20 oct. 2026 | 00:36:32 | |
Can an athlete reduce the environmental impact of their diet while still meeting the demands of training, competition and recovery? Peter Res argues that these aims can be compatible, provided dietary changes are planned around the athlete's needs. The discussion looks at practical changes athletes can make to make their diets more environmentally sustainable. This includes tips on increasing the contribution of plant proteins, maintaining adequate energy intake, and making plant-rich eating practical within sporting environments. Timestamps
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| #623: Testosterone Testing: What Do the Results Mean? When Does TRT Help? – Austin Baraki, MD | 13 oct. 2026 | 01:08:19 | |
Men commonly feel that if their testosteone isn't "optimized" and high, they are missing out on greater health in a variety of ways. But what can a testosterone result actually tell us? How can results be interpreted with appropriate nuance that is needed? How low is low enough to be problematic? In situations where a test flags testosterone as low, there is a belief this means automatically starting testosterone replacement therapy. While TRT can be an excellent intervention in appropriate cases, when is it actually likely to benefit someone, and when is it not? For many people the decision seems straightforward: get a blood test, see whether testosterone is a little low, and start TRT. However, this simplistic thinking is full of potential issues that are important to understand. Dr. Austin Baraki returns to discuss how testosterone testing should inform treatment decisions, what benefits to expect, and the questions surrounding fertility and long-term safety. Timestamps:
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| #622: Body Composition Testing: Methods & Interpretation – Prof. Grant Tinsley | 06 oct. 2026 | 01:04:02 | |
Body composition testing is widely used in research, sport and clinical practice. But what are these methods actually measuring, and how much confidence should we place in the numbers they produce? In this episode, we examine the assumptions behind common approaches including DXA, bioelectrical impedance, and skinfold measurements. We discuss the distinction between accuracy and reliability, the value and limitations of repeated measurements, and how coaches, clinicians, researchers and individuals can select an appropriate method and interpret the data without overstating its precision. Joining Danny to discuss these issues is Professor Grant Tinsley, Professor of Human Performance at Texas Tech University and Director of its Energy Balance and Body Composition Laboratory. Timestamps:
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| #621: Hedonic Overeating, Food Wanting and Impact of Perception – Prof. Graham Finlayson | 22 sept. 2026 | 00:42:39 | |
Why do some foods feel difficult to stop eating, while others can be highly enjoyable without prompting the same tendency to overconsume? Answering this requires a clearer understanding of food reward, including the distinction between liking a food, wanting it, and perceiving it as easy to overeat. In this episode, we examine how nutritional composition, sensory characteristics, learned beliefs and the eating context may shape hedonic overeating. It also considers the limits of using broad food categories to explain complex eating behaviour. Discussing all this is Professor Graham Finlayson, professor of Psychobiology at the University of Leeds, whose research focuses on human appetite, food reward and the psychological processes involved in eating behaviour and weight control. Timestamps
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| #620: BPC-157 and Peptide Medications: What Do We Know? – Jordan Feigenbaum, MD | 15 sept. 2026 | 00:57:32 | |
Commonly people are talking about "peptides" to refer to a heterogeneous group of peptide medications or investigational compounds. These are increasingly promoted for injury recovery, tissue repair, performance and longevity, with BPC-157 attracting particular attention. But what evidence supports the claims made about these compounds? How should animal studies, biological mechanisms and personal anecdotes be interpreted? What is currently known about their safety? And what do recent regulatory discussions actually mean for their medical status and availability? In this episode, physician and Barbell Medicine founder Dr. Jordan Feigenbaum examines the evidence surrounding BPC-157 and other peptide medications, alongside the wider questions of risk, access and informed decision-making. Timestamps
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| #619: How Much Fish Should a Healthy Diet Contain? | 08 sept. 2026 | 01:03:22 | |
Most dietary guidelines recommend eating one to two servings of fish per week, often specifying that at least one serving should be oily fish. But how directly is that recommendation supported by evidence? And does adding fish to the diet improve outcomes? This episode examines where current fish-intake recommendations originated, why findings may appear contradictory, and what substitution analyses can tell us about replacing fish with alternative options. It also considers evidence from pescatarian and vegetarian cohorts, including whether adding fish would improve an already high-quality diet and whether removing it from a plant-forward diet is likely to provide further benefit. Timestamps
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| #618: How Wellness & Optimisation Culture Can Commodify Science – Nick Tiller, PhD | 01 sept. 2026 | 00:56:55 | |
Wellness and optimisation culture increasingly presents itself as "science-based". But citing studies, using technical language, or having scientific credentials does not guarantee that the underlying evidence is being represented accurately. In this episode, exercise science researcher Dr. Nick Tiller, discusses how science can be selectively packaged, overstated, and used to support commercially attractive health claims. It explores the difference between science communication and science commodification, why scientific scepticism is distinct from cynicism, how anecdotes and mechanistic explanations can mislead, and why a single peer-reviewed study should never be treated as definitive evidence. The conversation also looks further upstream at problems within science itself, including low statistical power, p-hacking, publication bias, questionable research practices, and academic incentives that may favour novelty and positive findings. These issues can then be amplified through media, social platforms, and the wellness industry until tentative findings become confident recommendations. Timestamps:
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| #617: What Does Effective Athlete Support Look Like in Practice? – Gemma McGuinness | 25 août 2026 | 00:46:40 | |
Effective athlete support requires more than delivering technically correct nutrition advice. It depends on understanding the athlete's wider environment, anticipating the pressures that disrupt good intentions, and building flexible routines that remain useful across training, competition, travel and everyday life. This episode explores how practitioners can move beyond rigid prescriptions, use "good, better, best" options, measure meaningful progress, and create environments in which athletes can communicate openly about difficulties. It also examines identity, transitions out of sport, and why sustainable support should develop an athlete's autonomy rather than dependence on the practitioner. To discuss all this is Gemma McGuinness, registered performance nutritionist, former professional footballer and co-founder of Verus Performance. Timestamps:
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| Fiber: Independent Benefits or Just a Proxy for Healthy Foods? | 18 août 2026 | 00:21:00 | |
This episode answers one of the questions raised in the most recent Q&A episode on Sigma Nutrition Premium. The full episode includes the following questions:
To listen to the entire episode (plus the back catalogue of all Premium-exclusive episodes) become a member of Sigma Nutrition Premium. For episode info and mentioned research go to the episode page here. | |||
| #616: More Testing, Better Health? Harms of Overdiagnosis & Overtreatment - Austin Baraki, MD | 11 août 2026 | 01:15:28 | |
Medical screening is often framed as an uncomplicated good: if disease is found earlier, treatment can begin earlier and outcomes should improve. This episode examines why that reasoning is incomplete. Screening can produce benefit, but it can also generate false positives, incidental findings, overdiagnosis, overtreatment and diagnostic cascades. Dr. Austin Baraki discusses the distinction between screening people without relevant symptoms and investigating a clinical problem, the probabilistic interpretation of test results, biases that can make screening appear more effective than it is, and the importance of shared decision-making before a test is ordered. Timestamps:
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| #615: Why Processing Doesn't Determine the Healthfulness of Plant-Based Diets – Alysha Thompson, PhD | 04 août 2026 | 00:56:18 | |
What does the evidence actually show when we look at plant-based dietary patterns through the lens of food processing? And does classifying foods as "ultra-processed" meaningfully change how we interpret the relationship between plant-based diets and long-term health outcomes? A recent large prospective cohort analysis examined both healthful and unhealthful plant-based dietary patterns, and importantly, stratified the contributing foods based on whether they were classified as ultra-processed or non-ultra-processed. In this episode, the study's lead author Dr Alysha Thompson, discusses the many intesresting aspects to the analysis. These include how the dietary indices were constructed, the challenges of applying NOVA classification to self-reported dietary data, the role of residual confounding in observational nutrition research, and the extent to which we can or cannot infer independent effects of processing from these findings. We also consider the broader implications for the use of processing-based classifications in nutrition science and whether this adds meaningful explanatory value beyond traditional assessments of diet quality. Timestamps
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| #614: The Human Skills of Nutrition Coaching – Krista Scott-Dixon, PhD | 21 juil. 2026 | 00:56:30 | |
In nutrition and health coaching, one of the central challenges is understanding how people actually change, particularly when life is complex, motivation fluctuates, and behaviour is shaped by emotion, identity, environment, and relationships. In this episode, Dr. Krista Scott-Dixon discusses the human skills that underpin effective coaching practice. We discuss the importance of the coach–client relationship, the role of therapeutic alliance, and how concepts from counselling and psychology can be used appropriately within scope of practice. The discussion also explores autonomy-supportive coaching, self-regulation, compassion, acceptance, feedback, and the meta-skills practitioners need in order to improve over time. Timestamps
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| #613: Supplement Safety & Medication Interactions – Giulia Guerrini, MPharm | 14 juil. 2026 | 00:57:18 | |
Supplement safety is often discussed in very general terms, but in practice the risks depend heavily on the individual. A supplement that is reasonable for one person may be inappropriate for another based on their medications, health conditions, dose, formulation, or the other products they are already using. This becomes especially important when supplements interact with medications or underlying medical conditions. Some interactions can change how a drug is absorbed, metabolised, transported, or cleared from the body. Others can amplify or oppose the drug's clinical effect, such as increasing sedation, lowering blood pressure or blood glucose, or affecting bleeding risk. In this episode, Giulia Guerrini, a GPhC-registered pharmacist and researcher at Examine, talks about how clinicians and practitioners can think more systematically about supplement safety, side effects, contraindications, and drug–supplement interactions. Timestamps:
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| #612: Does Sweet Taste Exposure Actually Develop Preference? – Prof. Katherine Appleton | 07 juil. 2026 | 00:38:59 | |
A common idea is that repeated exposure to sweet taste strengthens our preference for sweetness, which then drives greater intake of sweet foods and drinks. This idea is often used in arguments about fruit, low-calorie sweeteners, diet drinks, and the supposed need to "reset" taste preferences by avoiding sweetness altogether. But does the evidence actually support that causal chain? In this episode, Prof. Katherine Appleton, Professor of Psychology at Bournemouth University, discusses what is known about sweet taste exposure, sweet preference, and how these concepts are measured in the scientific literature. Timestamps:
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| #611: Electrolyte Mythology: Wellness Marketing vs. Evidence - Zoë Rom & Kylee Van Horn | 30 juin 2026 | 00:55:08 | |
Electrolytes have become one of the most heavily marketed areas of modern sports nutrition and wellness. What was once a relatively specific tool for certain endurance athletes has increasingly been reframed as an everyday requirement for hydration, energy, focus, productivity, and general health optimisation. But how much of this messaging is grounded in physiology, and how much is an example of industry taking a real mechanism and extending it far beyond the evidence? In this episode, we examine why many common use cases are unlikely to require an electrolyte product. Along the way, we explore how wellness marketing, biohacking culture, diet communities, and social media narratives can turn narrow sports nutrition applications into broad claims that many people come to accept as true. To discuss this topic, Danny is joined by Zoe Rom, a science and environmental journalist, and Kylee Van Horn, a sports dietitian, to discuss how these claims are shaped by marketing, culture, and the attention economy. Timestamps:
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| SNP51: Understanding Blood Glucose Reponses | 23 juin 2026 | 00:13:26 | |
This is a Premium-exclusive episode. Go to the Premium feed to listen. Or subscribe to Premium. Blood glucose is easy to measure, but not always easy to interpret. This Premium-only episode brings together insights from several previous guests to examine blood glucose responses in more detail. We discuss the misuse of clinical thresholds, the difference between OGTT results and free-living CGM data, and whether "flatter" glucose curves are actually better in normoglycemic people. The episode also covers when repeated high glucose excursions may be worth investigating, how sugar intake should be interpreted in context, and why skeletal muscle and exercise play such an important role in glucose regulation. Overall, the aim is to clarify what glucose responses can tell us, what they cannot tell us, and how to avoid pathologizing normal physiology. Links:
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| #610: Rock, Paper, Salmon – Errors in Interpreting Food Substitution Models | 16 juin 2026 | 00:57:04 | |
When considering the health impact of foods, it is important to consider "compared to what?". Increasing the amount of a certain food or nutrient in the diet, typically implies a displacement of another. While comparisons are more obvious in trials, in epidemiology food substitution models can be useful to help us determine the health effects of increasing/decreasing intake of a food, food group or nutrient. However, these models are often misinterpreted and miscommunicated as if they are a game of "rock, paper, scissors", where one food beats another, and the losing food must be removed from the diet or considered harmful to health. In this episode we discuss the problem of treating substitution analyses as food-ranking contests, rather than context-dependent comparisons shaped by the comparator, the unit of substitution, the baseline diet, and the outcome being studied. Timestamps:
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| #609: Unprocessed Red Meat & Cancer Risk | 09 juin 2026 | 01:09:44 | |
Unprocessed red meat and cancer risk remains one of the most debated topics in nutrition science, partly because the evidence is often presented in overly simplistic terms. The key question is not whether to adopt a vague "balanced" position on red meat, but whether the evidence clearly identifies intake levels at which colorectal cancer risk increases and whether controlled human trials support plausible mechanisms for that risk. A second issue is whether claims that fibre, vegetables, or an otherwise "healthy diet" can neutralise high red meat intake are actually supported by the mechanistic evidence, or whether they overstate what dietary context can plausibly offset. In this episode, Danny and Alan examine the evidence base by moving beyond the usual epidemiology-only debate. They discuss why regional intake patterns and dose thresholds matter, then explore controlled human feeding studies showing how higher red meat intake can increase endogenous N-nitroso compound formation, faecal water genotoxicity, and other mechanistic biomarkers linked to colorectal carcinogenesis. Timestamps:
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| #608: Performance Nutrition in Elite Rugby – James Morehen, PhD | 02 juin 2026 | 01:08:02 | |
Performance nutrition in elite sport is often discussed in terms of meal plans, supplements, and macronutrient targets. However, effective practice in professional environments depends just as much on education, trust, communication, and the ability to translate scientific principles into decisions athletes can act on under real-world constraints. In this episode, Dr James Morehen discusses his work across elite rugby, football, and combat sports, with particular attention to the demands of professional rugby. The conversation explores how practitioners support athletes in a high-impact collision sport, including fuelling for training and match play, managing body composition without reducing athletes to arbitrary numbers, addressing recovery from muscle damage and injury, and developing practical systems around game-day nutrition. The episode also provides insight into the realities of building a career in performance nutrition, including the importance of applied experience, interdisciplinary collaboration, and learning how to coach athletes rather than simply prescribe to them. Timestamps:
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| #607: Gut Health & Microbiome Testing: What Evidence Do We Actually Have? – Emily Leeming, PhD | 26 mai 2026 | 00:50:41 | |
Gut health has become a major focus in nutrition, medicine, and consumer wellness, but the term is often used loosely. Claims about microbiome testing, probiotics, fermented foods, fibre, and "boosting" the gut microbiome are now common, yet the evidence behind these claims varies substantially. In this episode, Dr. Emily Leeming examines what gut health actually refers to, why it cannot be reduced to the microbiome alone, and where current microbiome science is being applied before it is ready. The discussion covers the limits of commercial stool testing, the difficulty of defining a healthy microbiome, and the practical strategies most strongly supported by current evidence. Timestamps:
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| PMOS (PCOS) and Diet: What Can Nutrition Realistically Do? - SNP#50 | 21 mai 2026 | 00:19:13 | |
In this episode, we examine what nutrition can realistically do in the condition historically known as PCOS, now renamed polyendocrine metabolic ovarian syndrome, or PMOS. We begin by explaining why the name change matters: the condition is not defined by ovarian cysts, but is better understood as a broader endocrine-metabolic and ovarian syndrome involving insulin resistance, androgen excess, ovulatory dysfunction, metabolic risk, and psychological burden. We then assess the nutrition evidence, including energy restriction, weight loss, carbohydrate quality, glycaemic index and load, protein intake, fat quality, appetite regulation, fertility outcomes, and phenotype differences. Rather than seeking a single "PCOS diet", the episode asks which dietary features may plausibly help, how strong the evidence is, and where uncertainty remains. This is a Premium-exclusive episode. To listen to the full episode, subscribe to Premium. Links:
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| #606: Practical Nutrition Strategies for Fat Loss – Luke Hanna | 19 mai 2026 | 00:41:23 | |
Body composition goals, particularly bodyfat loss, are among the most common reasons people seek support from a nutritionist or health and fitness professional. While the principles are well established, the challenge is helping individuals apply them consistently in real-world conditions. Many people struggle due to hunger, unrealistic expectations, emotional eating, inconsistent routines, or overly restrictive dieting approaches. These challenges can make fat loss difficult to sustain, even when someone understands what they "should" be doing. In this episode, Luke Hanna discusses practical strategies for improving body composition, including food diaries, energy-density manipulation, preloads, mindful eating, and realistic goal-setting. The discussion emphasizes identifying individual barriers, collaborating with clients, and building repeatable behaviours that support both fat loss and long-term maintenance. Luke Hanna holds a Master's degree in Obesity and Clinical Nutrition from University College London and a degree in Sport and Exercise Science from the University of Portsmouth. He currently works as a nutrition coach and personal trainer. Timestamps:
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| #605: Fasting, Nutrient Timing & CGMs: Interpreting the Evidence – Prof. James Betts | 12 mai 2026 | 00:56:13 | |
Fasting, nutrient timing, chrono-nutrition, and continuous glucose monitoring are all topics that have generated substantial interest, but they are also areas where exaggerated claims can easily outpace the underlying evidence. In many cases, tentative hypotheses are presented as if they were already well-established conclusions, despite the fact that the research base is often more mixed and context-dependent than popular narratives imply. It is one thing for an idea to appear biologically coherent. It is another for that idea to translate into meaningful, reliable effects in real-world interventions. In this episode, Professor James Betts discusses how to think clearly about these topics, why common errors in interpretation can lead to overstated conclusions, and what is required to properly evaluate whether an observed effect reflects a true intervention effect rather than baseline differences, inappropriate comparisons, within-group changes, or mechanistic signals being mistaken for meaningful health outcomes. Timestamps:
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| #604: How To Interpret Nutrition Research – David Allison, PhD | 05 mai 2026 | 00:52:16 | |
How should we decide what counts as trustworthy evidence? Scientific rigor is not a single characteristic of a study, but a chain of decisions made from the moment a question is conceived to the point at which findings are communicated to the public. Errors can occur at every stage: the question may be ill-posed, the design may be incapable of answering it, the measurements may be weak, the analysis may be inappropriate, the interpretation may overreach, and the public-facing communication may become distorted. In this episode, Dr. David Allison, PhD discusses the deeper methodological issues that shape the field's conclusions. The discussion moves from the philosophy of scientific inquiry to the practical realities of study design, statistical analysis, interpretation, and dissemination. Timestamps:
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| #603: Should Dietary Fiber Be Considered Essential? – Andrew Reynolds, PhD | 28 avr. 2026 | 00:59:14 | |
Dietary fiber is widely recognized as an important component of a healthy diet, yet it is not typically classified as an essential nutrient. In this episode, Dr. Andrew Reynolds explores whether that distinction still holds, arguing that the traditional criteria used to define essentiality may be outdated when applied to modern nutrition science. The discussion moves beyond simply acknowledging the benefits of fiber and instead examines whether it meets the foundational requirements of an essential nutrient. This includes considering its physiological roles, the body's inability to synthesize it in sufficient quantities, and whether low intake leads to a meaningful and reversible dysfunction. Drawing on evidence from prospective cohort studies, randomized controlled trials, and mechanistic research, Reynolds outlines the strength of the evidence linking higher fiber intakes to reduced risk of cardiovascular disease, type 2 diabetes, colorectal cancer, and premature mortality. Reynolds presents a compelling case that fiber may play a fundamental role in maintaining normal physiological function and therefore warrants reconsideration within the framework of essential nutrients. Timestamps:
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| #602: Avoidant/Restrictive Food Intake Disorder (ARFID) – Megan Hellner, DrPH, RD & Katherine Hill, MD | 21 avr. 2026 | 00:50:27 | |
Avoidant/Restrictive Food Intake Disorder (ARFID) is an eating disorder diagnosis characterized by a persistent restriction or avoidance of food intake that results in clinically significant consequences (medical, nutritional, and/or psychosocial), but without the weight- and shape-driven psychopathology typical of anorexia nervosa and bulimia nervosa. In this episode, Megan Hellner and Katherine Hill outline how ARFID presents across the lifespan, why it is frequently missed in routine healthcare, and what an evidence-informed assessment and treatment pathway can look like in practice. A central theme is that ARFID is not synonymous with "picky eating" and not confined to any one body size. Patients may present at any point on the weight chart, including those who are weight-stable or in larger bodies, and the condition can begin in early childhood and persist into adulthood. The episode also highlights ARFID in athletes and physically active people, where restricted dietary variety and/or low intake can contribute to low energy availability and RED-S-like presentations, sometimes without an obvious intent to lose weight. Timestamps
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| #601: Gallstones & Gallbladder Conditions: Impact of Diet – Angela Madden, PhD RD | 14 avr. 2026 | 00:53:26 | |
This episode examines what we actually know (and importantly, what we do not know) about diet in relation to gallstones and gallbladder conditions. Much of the public-facing guidance around gallstones focuses on "avoiding fatty foods", yet Dr. Angela Madden explains that this long-standing practice sits on surprisingly weak direct evidence, particularly when judged against the standards typically expected for clinical dietary recommendations. A central theme is the need to separate two distinct questions: dietary factors that influence the risk of developing gallstones (prevention), versus dietary strategies intended to reduce symptoms or complications once gallstones exist (management). While the prevention literature suggests plausible, consistent associations with overall diet quality and lifestyle factors, the specific question of prescribing a low-fat diet to manage symptomatic gallstones lacks robust randomized trial evidence. Dr Angela Madden is a clinical researcher in nutrition and dietetics at the University of Hertfordshire, where she established and led the nutrition and dietetics subject group and now focuses her research on improving nutritional assessment, dietary interventions, and patient-centred outcomes in clinical and public health settings. Timestamps
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| Coevolution With Foods? Multivitamins? Eating Too Early? – Ask Me Anything (SNP49) | 07 avr. 2026 | 00:22:09 | |
In this episode, Danny answers questions submitted by Premium subscribers. Questions Answered in This Episode:
To listen to the full episode, subscribe to Sigma Nutrition Premium. Related Resources
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| #600: Finite Knowledge, Infinite Ignorance | 31 mars 2026 | 02:00:12 | |
"The more we learn about the world, and the deeper our learning, the more conscious, specific, and articulate will be our knowledge of what we do not know, our knowledge of our ignorance. For this, indeed, is the main source of our ignorance — the fact that our knowledge can be only finite, while our ignorance must necessarily be infinite." – Karl Popper To mark Sigma Nutrition's milestone 600th episode (and 12-year anniversary), Danny and Alan examine several areas in which their views have changed, softened, strengthened, or remained stable over the lifespan of the podcast. The discussion is therefore not only about nutrition itself, but also about the process of scientific reasoning: how positions are formed, what type of evidence can shift them, and why changing one's mind is often a sign of better thinking rather than inconsistency. The episode therefore serves as both a review of several specific nutrition controversies and a lesson in scientific epistemology. They discuss topics such as red meat, protein, dietary cholesterol, omega-3s, flavonoids, and sodium. Timestamps
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| #599: Does Unprocessed Red Meat Increase Diabetes Risk? – Gil Carvalho, PhD MD & Mario Kratz, PhD | 24 mars 2026 | 01:18:33 | |
This episode examines whether unprocessed red meat has a causal role in (1) type 2 diabetes risk and intermediate measures of glucose intolerance (insulin resistance, beta cell dysfunction, glycemic markers) and (2) cardiovascular disease (CVD) risk. While there is commonly observed risk signal from observational cohorts, there exist short-term randomized controlled trials (RCTs) that show largely null effects on glucose homeostasis. This had led to differing opinions and interpretations of the evidence base. Some feel that in the context of an otherwise healthy diet, there isn't much to suggest concern about consuming unprocessed red meat. While others are of the view that there does exist a risk and that limiting or even avoiding consumption is prudent. The crucial concept of replacement effects is discussed. Increasing red meat intake always means decreasing something else or increasing total energy intake. Therefore, interpreting evidence requires specifying the comparator food(s), the background dietary pattern, the dose, the cut (lean vs fatty), and how the meat is prepared. To discuss their interpretations of this contentious evidence base, Dr. Mario Kratz and Dr. Gil Carvalho join the podcast to go through the studies most directly related to these questions. Timestamps
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| #598: How Do Exercise & Diet Interact to Improve Glycaemic Control? – Jenna Gillen, PhD | 17 mars 2026 | 00:44:24 | |
This episode examines how exercise and nutrition interact to influence glycaemic control, with particular focus on the postprandial period (i.e., the hours after eating) and on "time-efficient" exercise strategies such as low-volume interval training. Dr. Jenna Gillen outlines the physiological basis for why muscle contraction can acutely reduce post-meal glucose excursions, why repeated sessions can accumulate into longer-term improvements in insulin sensitivity, and why the nutrition context (pre- and post-exercise feeding, carbohydrate availability, and energy balance) can meaningfully alter observed outcomes. A key translational thread is that many clinically relevant improvements may come from small, feasible doses of activity; especially post-meal walking and brief "exercise snacks" used to interrupt sedentary time. However, the discussion considers who these interventions matter for most (and least). Postprandial glucose rises are normal in healthy individuals, whereas reducing exaggerated excursions is most relevant for those with insulin resistance, prediabetes, or type 2 diabetes (T2D). Dr. Jenna Gillen is an Assistant Professor of Exercise Physiology in the Faculty of Kinesiology & Physical Education at the University of Toronto. Timestamps
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| #597: Behavioral Psychology in Diet & Health Counselling – David Creel, PhD, RD | 10 mars 2026 | 00:51:43 | |
In clinical practice effective nutrition, exercise, and obesity care is rarely about identifying the single "best" plan on paper. Instead, sustainable change depends on behavioral psychology: understanding the person's context, motivation, barriers, and patterns, then co-designing practical steps that can actually be implemented in real life. David Creel PhD, RD is a clinical psychologist and registered dietitian working in weight management at the Cleveland Clinic. Dr. Creel discusses how clinicians can bridge the gap between "optimal recommendations" and what is most likely to create actual behaviour change. This includes a combination of using collaborative communication, self-monitoring, skill-building, relapse prevention planning, and a multidisciplinary framework. Behavioral and psychological factors shape food choices, physical activity, and adherence far more than knowing the newest guideline. In addition, the modern obesity treatment landscape (including GLP-1 receptor agonists) increases the need for structured behavior-change support: people may experience new hope and new fear (especially fear of weight regain), and the key clinical question becomes how to use these tools to build durable habits and reduce relapse risk over the long term. Timestamps
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| #596: Why Do Omega-3 Trials Show Mixed Results? | 03 mars 2026 | 01:06:11 | |
Omega-3 fatty acids (particularly EPA and DHA) have a long history in nutrition and cardiovascular medicine, yet the clinical trial literature is often perceived as inconsistent. This episode examines why some randomized trials show clear benefit while others show null or mixed findings, and how differences in trial design, dose, population risk, and outcome selection can materially change what we observe. A key theme is separating (1) the persistent cultural narratives around omega-3s (including origin stories that do not hold up well to modern evidence) from (2) the more precise, mechanistic and clinical questions about where supplemental EPA/DHA may reduce cardiovascular risk. The discussion focuses heavily on understanding heterogeneity: why "omega-3 supplementation" is not a single, uniform exposure, and why subgroup patterns (e.g., secondary prevention, higher baseline triglycerides, and higher doses) may explain much of the apparent conflict in the evidence. Note: This discussion is taken from a previous episode of the podcast. The audio has been remastered and improved, and now study notes and full transcript are available. Timestamps
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| #595: Neuroplasticity and Reducing Risk of Cognitive Impairment – Dr. Majid Fotuhi | 24 févr. 2026 | 00:38:21 | |
Conversations about brain health have been dominated by a competing mix of fatalism and over-promising, with aging framed as inevitable decline and "brain optimisation" sold through weak evidence. So how should we think about cognition across the lifespan? In this episode, we explore the idea that neuroplasticity does not disappear in adulthood, but instead continues to respond, for better or worse, to repeated behaviours and exposures. Much of what is labelled age-related cognitive decline may in fact reflect an accumulation of modifiable risk factors. We also dig into how to critically evaluate brain-health claims and how lifestyle pillars such as exercise, sleep, diet, stress reduction and cognitive training fit into a coherent framework. The discussion extends to emerging multimodal intervention programs, their promising signals and their clear limitations, and to a broader, multifactorial view of Alzheimer's disease that moves beyond a narrow amyloid-centric model. Finally, we examine the role of genetics, including ApoE4, and why genetic risk does not equate to biological destiny, even later in life. Dr. Majid Fotuhi is a neurologist and an adjunct professor at the Johns Hopkins Mind/Brain Institute. He earned his medical degree from Harvard Medical School and completed a Ph.D. in neuroscience at Johns Hopkins University. That was followed by internship and neurology residency at Johns Hopkins Hospital. Timestamps
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| How Much Dietary Fiber Do We Need to be Healthy? (SNP48) | 17 févr. 2026 | 00:20:45 | |
This is a Premium-exclusive episode of the podcast. To listen to the full episode you need to be subscribed to Sigma Nutrition Premium. This episode examines dietary fiber through the lens of a practical, clinically relevant question: if higher fiber intakes are consistently associated with reduced chronic disease risk, what intake level should we be aiming for to meaningfully improve health outcomes? The discussion deliberately spans from common online claims that fiber is "not essential" (and therefore unnecessary), through to mechanistic reasoning and the highest-quality evidence we have for hard outcomes and accepted intermediate cardiometabolic endpoints. Across the episode, we'll hear from six expert perspectives to integrate epidemiology, controlled feeding studies, and clinical guideline contexts. We will consider how the dose–response patterns, fiber type/source, individual tolerance, and the limitations of nutrition trials all influence what can be recommended with confidence. Timestamps
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| #594: Can Muscle Still Adapt Positively When Training Under Low Energy Availability? – Jose Areta, PhD | 10 févr. 2026 | 00:49:02 | |
Dr. José Areta and colleagues recently carried out a human intervention study examining how a pronounced, short-term energy deficit interacts with an aerobic training stimulus to shape endocrine, metabolic, and skeletal muscle proteomic adaptations. The core premise is that "low energy availability" is often discussed in a largely unidirectional risk framework, yet human physiology evolved under intermittent energy scarcity, and therefore adaptive responses may be more nuanced than "energy deficit equals impaired adaptation." The study used tightly controlled diet and exercise, repeated muscle biopsies, and dynamic proteomic profiling to quantify both abundance and synthesis rates of hundreds of individual muscle proteins. This enables a more granular view of "muscle quality" and phenotype than traditional bulk muscle protein synthesis measures. The findings were incredibly interesting and could have implications for how we view the impact of energy deficits and exercise response. We discuss the implications for athletes who routinely encounter transient within-day or multi-day energy deficits, for weight loss contexts, and for broader questions around healthspan and ageing biology. Timestamps
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| #593: Can We Define Hyper-Palatable Foods? And Is Processing Actually the Problem? – Tera Fazzino, PhD | 03 févr. 2026 | 00:51:28 | |
While the term "hyperpalatable" has been used frequently for considerable time to refer to foods that are so appealing and tasty that they drive overeating, this term hasn't been well-defined nor has there been a universal standard for what it means. One researcher who set out to create an objective definition for hyper-palatable foods (HPFs) is Dr. Tera Fazzino. Using specific defined thresholds of sugar, fat and salt combinations, Dr. Fazzino and colleagues have looked at the impact of consumption of these HPFs. In this episode, we delve into defining HPFs and their nutrient profiles, whether they have addictive-like properties, how HPFs differ from (and overlap with) ultra-processed foods (UPFs), the mechanisms by which these foods drive overconsumption, and the broader public health implications. Tera Fazzino, PhD, is an associate professor of psychology at the University of Kansas. Her research focuses on addiction, obesity, and eating-related behaviors. Timestamps
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| #592: How Much Protein is Actually Healthy? – Eric Helms, PhD & Matt Nagra, ND | 27 janv. 2026 | 01:26:11 | |
In this episode, the discussion turns to a deceptively simple question that sits at the centre of countless nutrition debates: how much protein do we actually need? On one side, there are confident claims that very high protein intakes are not just beneficial but essential for maximising strength, performance, and muscle mass. On the other, equally strong assertions that the current RDA is entirely sufficient for most people, and that going beyond it is unnecessary or even harmful. Dr. Eric Helms and Dr. Matthew Nagra work through what the evidence actually tells us when we step away from slogans and thresholds. What does 0.8 g/kg represent, and just as importantly, what does it not? At what point do higher intakes stop meaningfully improving muscle-related outcomes? And where do concerns about kidney function, longevity, and chronic disease fit when we look at long-term data rather than isolated mechanisms? Rather than treating protein as a single number to defend or dismiss, this conversation places intake in context: training status, ageing, health outcomes, source and optimising for specific goals. Timestamps
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| #591: Maintaining Functional Capacity with Age – Brendan Egan, PhD | 20 janv. 2026 | 00:52:31 | |
Maintaining the ability to carry out everyday tasks and live independently is often described as a cornerstone of healthy ageing. But what actually happens to muscle strength, power, and functional ability as we get older? And how inevitable is their decline? At what point do changes in muscle function really begin to matter for day-to-day life? Is loss of strength an unavoidable consequence of ageing itself, or does it reflect something more modifiable? If declines are not fixed, what kinds of training or lifestyle interventions genuinely make a difference, and how strong is the evidence behind them? In this episode, exercise physiologist Dr Brendan Egan examines these questions through the lens of both epidemiological data and controlled training studies in older adults. What do we learn from short-term resistance training interventions lasting just a few months? Do the gains persist once supervised training ends? And what does this tell us about the practical challenges of maintaining functional capacity over the long term? The conversation also explores the idea of "use it or lose it" in muscle function, the role of resistance training in extending healthspan, and how exercise programmes can be designed to support independence later in life. Ultimately, the episode asks a simple but crucial question: what does the evidence actually say about staying strong, capable, and functionally independent as we age? Dr. Brendan Egan is an Associate Professor of Sport and Exercise Physiology the School of Health and Human Performance at Dublin City University. Currently, he is Associate Dean for Research in the Faculty of Science and Health. Timestamps
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| #590: Is the Nutrient Density of Crops Declining? – Edward Joy, PhD | 13 janv. 2026 | 00:41:09 | |
Nutrient density refers to the concentration of vitamins and minerals in crops relative to their yield. There are widespread claims that today's fruits, vegetables, and grains contain fewer micronutrients than in decades past, often linked to modern farming practices or soil degradation. This issue is important because if staple crops become less nutritious, it could silently undermine dietary quality and contribute to micronutrient deficiencies ("hidden hunger") in populations. Dr. Edward Joy is uniquely qualified to address this topic. As a senior research fellow in food systems and nutrition at Rothamsted Research and an associate professor at the London School of Hygiene & Tropical Medicine, his work centers on the intersection of agriculture and nutrition. In this conversation, Dr. Joy draws on evidence from agronomy and public health to clarify whether the nutrient content of crops has indeed declined, what factors might be responsible (from soil health to plant breeding and climate change), and what we can do to improve the situation. The discussion emphasizes an evidence-based perspective on soil nutrients, crop varieties, and interventions, cutting through myths to identify real concerns and practical solutions. Timestamps
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| Does Processing Really Make Food Unhealthy? (SNP47) | 06 janv. 2026 | 00:17:53 | |
This is a Premium-exclusive episode of the podcast. To listen to the full episode you need to be subscribed to Sigma Nutrition Premium. Recently we (Danny Lennon & Alan Flanagan) were invited to 'Processing the Evidence', a "behind closed doors" workshop to discuss the latest scientific evidence on the role of processed foods in human health. The event was organized by Professors Ciarán Forde and Vincenzo Fogliano of Wageningen University in the Netherlands. The workshop attendees included a range of prominent researchers across a range of domains related to food processing, nutrition science, and public health. The sessions included open discussions on current evidence, knowledge gaps and challenges within the UPF debate. There were several structured sessions looking at different sub-topics, such as:
In this episode, Alan and Danny review some of the key talking points and their takeaways from this event. Timestamps
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| #589: Causal Inference in Nutrition Science – Daniel Ibsen, PhD | 30 déc. 2025 | 01:01:24 | |
This episode explores how asking better questions and using stronger methods can resolve much of the confusion in nutrition science. Dr. Daniel Ibsen discusses why nutrition research often produces conflicting results and how careful methodological thinking can clarify true diet-disease relationships. Nutrition science has unique challenges – diets are complex, people self-report their food intake imperfectly, and we can't easily run long-term diet experiments on people. Dr. Ibsen explains how embracing concepts like food substitution analysis, the "target trial" framework, and objective dietary assessment can strengthen evidence. The episode centers on methodological insights that make nutrition research more reliable and actionable. Key themes include defining dietary comparisons explicitly (the "compared to what?" question), considering people's starting diets, and using causal inference techniques to design better studies. Daniel B. Ibsen is an epidemiologist and nutritional scientist whose work bridges rigorous causal inference methods with real-world diet and cardiometabolic disease research. He is an Associate Professor at Aarhus University, Denmark. Timestamps
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| #588: Menstrual Cycle "Syncing": Do the Claims Hold Up to Evidence? – Expert Panel | 23 déc. 2025 | 00:46:14 | |
How much do hormonal fluctuations really influence performance and recovery? Should women be adjusting their training and nutrition based on the menstrual cycle? And do female athletes need different protein strategies or recovery protocols than men? These are questions that have fuelled countless online claims, from rigid "cycle syncing" programmes to supposedly gender-specific nutrition rules. But how much of that is actually grounded in evidence? In this episode, the conversation tackles those debates head-on, exploring what we truly know about female physiology, adaptation, and recovery, and where confident narratives outpace the science. You'll hear from four leading experts: Professors Kirsty Elliot-Sale, Stu Phillips, Shona Halson, and Dr. Eric Helms, as they unpack the data on menstrual-cycle variation, autoregulation, and the real determinants of muscle growth and recovery in women. These discussions were originally recorded live as part of "The Inside Advantage" event hosted by Optimum Nutrition at the McLaren F1 Performance Centre in the UK, where Danny Lennon moderated the session. Timestamps
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| #587: How Should Nutrition Be Taught in Medical Training? – Akash Patel | 16 déc. 2025 | 00:44:07 | |
This episode centers on the critical gap in nutrition education within medical training and efforts to bridge it. Guest Akash Patel, a medical student who led a pilot nutrition curriculum, discusses why doctors receive little formal training in nutrition despite poor diet being a major driver of disease. With diet-related conditions (obesity, diabetes, cardiovascular disease, etc.) contributing heavily to morbidity and healthcare costs, the conversation highlights a pivotal push to better equip physicians in nutritional knowledge and counseling. Patel's work comes at a turning point: there are now calls for standardized nutrition competencies in medical education (e.g., a recent JAMA consensus) and a growing recognition that improving doctors' nutrition literacy could enhance patient care and public trust. But at the same time, medical programs already have a huge workload and little space is available for appropriate training. Others state that nutrition shouldn't fall within the remit of doctors. So how do we reconcile all this? While this episode focuses on the United States context, the concepts apply to other countries, as it outlines both the challenges and the emerging solutions for closing the nutrition training gap in medicine. Timestamps
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| #586: The Manufactured Collapse of Expertise | 09 déc. 2025 | 01:07:20 | |
Never before has there been greater access to information about nutrition and health. But never before has there been such a low barrier to being seen as an "expert". There are large numbers of people getting information from, and basing their health decisions on, people who don't have direct expertise in the field in which they are talking about. Moreover, some promote the lack of domain expertise as a feature, not a bug. They claim that those that were conventionally seen as domain experts are either brainwashed, lazy in their thinking, or outright corrupt. And the solution is instead to look to those with a fresh perspective that can illuminate us on the "truth". In this episode, Alan and Danny discuss this "death of domain expertise", how it plays out online, and its ramifications for people's ability to get good information. Note: This episode was originally published as an exclusive episode for Sigma Nutrition Premium subscribers. If you wish to get more Premium-only episode or read study notes to our episodes, you can subscribe to Sigma Nutrition Premium. Timestamps
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| SNP46: Reviewing Six Key Insights from the Year's Conversations | 02 déc. 2025 | 00:09:40 | |
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
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| #585: Why We Think Poorly: Reason, Emotion, and Evidence-Based Reasoning | 25 nov. 2025 | 00:58:44 | |
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
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| #584: EAT-Lancet: Does the Planetary Health Diet Improve Human Health? | 18 nov. 2025 | 00:59:19 | |
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
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| #583: Ultra-Processed Foods & Fixing the Food Environment – Kevin Hall, PhD | 11 nov. 2025 | 00:54:33 | |
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
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