Sigma Nutrition Radio

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 [03:48][06:23][09:36][11:37][16:46][18:59][25:16][29:16][32:28][35:44][38:16] Links/Resources Go to episode pageSigma Nutrition PremiumSigma email newsletterApplied Nutrition Literacy

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 [02:09][06:53][08:08][13:42][22:15][27:20][34:09][45:44] Related Resources episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition LiteracyDr. Madden's univeristy pageMadden et al., 2024 – Modified dietary fat intake for treatment of gallstone disease in people of any age513: Kidney Stones & Diet – Deepa Kariyawasam, RD

In this episode, Danny answers questions submitted by Premium subscribers. Questions Answered in This Episode: [00:05:13][00:16:55][00:32:54][00:44:56][00:56:25][01:04:46][01:12:37][01:19:18][01:23:58] To listen to the full episode, subscribe to Sigma Nutrition Premium. Related Resources Go to episode pageSigma Nutrition PremiumEckel et al., 2015 – Morning Circadian Misalignment during Short Sleep Duration Impacts Insulin SensitivityStothard et al., 2020 – Early Morning Food Intake as a Risk Factor for Metabolic DysregulationEp. #470: Melatonin, Meal Timing & Glucose ToleranceEp. #579: Is Your Chronotype Hard-Wired or Modifiable?Article: A Plant Based Diet Reverses Heart Disease: True or False?

"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 [11:04][19:32][35:04][51:38][01:05:23][01:23:10][01:44:41][01:53:41] Links Go to episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition Literacy

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 [06:20][10:54][15:31][24:43][33:13][45:49][50:43][01:00:30][01:08:10][01:11:36][01:16:19] Related Resources Go to episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition LiteracyNourished By ScienceNutrition Made Simple!

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 [02:42][04:11][10:07][11:10][20:10][26:27][31:29][36:32][40:11][43:56] Links Go to episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition LiteracySigma's recommended resources

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 [03:09][05:31][11:01][16:32][23:48][25:58][27:20][30:30][33:36][38:24][41:24] Related Resources Go to episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition LiteracyDr. David CreelDanny Lennon@drdavidcreel@NutritionDanny

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 [04:10][08:38][12:49][23:41][26:44][32:19][37:57][46:02][01:00:27][01:03:55] Related Resources Go to episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition LiteracyAlinea Nutrition Education Hub

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 [03:41][05:22][07:07][09:37][10:42][19:09][24:43][27:53][30:03][36:08] Related Resources Go to episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition LiteracyThe Invincible Brain

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 [03:51][11:23][17:16][20:01][26:48][36:07][41:57][43:23][54:06][01:01:47][01:16:18][01:21:45] Related Resources Sigma Nutrition Premiumepisode pageSigma email newsletterApplied Nutrition Literacy

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 [02:27][03:28][12:18][15:47][21:47][26:57][28:44][34:26][40:20][41:44][46:48]Premium Related Resources episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition Literacy@jlareta

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 [03:39][05:05][10:03][14:54][17:43][30:02][35:06][43:38][50:53] Related Resources episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition Literacy

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 [05:19][07:18][09:38][10:27][15:47][19:19][21:48][27:25][44:59][46:07][56:23][59:49][01:11:55][01:18:13][01:24:31] Related Resources Go to the episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition LiteracyMASS Research ReviewMuscle & Strength Pyramids books@helms3dmj@dr.matthewnagraDr. Nagra's website

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 [03:49][05:56][14:09][25:07][31:05][34:18][39:13][51:04] Links & Resources Go to episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition Literacy

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 [00:55][04:49][10:25][20:39][24:05][30:34] Related Resources episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition LiteracyRothamsted ResearchDr. Joy's profile page@edward_joy1@NutritionDanny

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 [00:31][04:44][07:52][11:53][21:51][33:21][38:10][47:19][50:19][54:18][01:00:55][01:08:03][01:23:12] Related Resources Sigma Nutrition Premiumepisode pageSigma email newsletterApplied Nutrition Literacy

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 [00:13][03:23][08:02][22:18][28:58][32:07][32:55][39:52][47:01] Links/Resources: the episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition Literacy

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 [02:07][07:46][09:22][10:23][15:01][17:28][18:46][26:29][29:20][34:01][45:08] Related Resources episode pageSigma email newsletterSigma Nutrition PremiumOptimum Nutrition's 'Inside Advantage' event

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 [03:21][05:22][07:55][13:37][15:11][23:38][29:00][33:58][38:15][43:07] Links & Resources Go to episode pageSigma email newsletterSigma Nutrition PremiumApplied Nutrition Literacy

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 [03:21][09:58][15:10][33:07][38:26][46:11][50:39][56:30] Links episode pageSigma email newsletterSigma Nutrition PremiumAlinea Nutrition Education HubApplied Nutrition LiteracyTom Nichols – The Death of ExpertiseJonathan Haidt – The Righteous MindIonnidis, 2018 – The Challenge of Reforming Nutritional Epidemiologic Research