Sigma Nutrition Radio

The podcast for lovers of nutrition science! Listen to detailed discussions with researchers and leading experts about the science of nutrition, dietetics and health.

#614: The Human Skills of Nutrition Coaching – Krista Scott-Dixon, PhD 07/21/2026

#613: Supplement Safety & Medication Interactions – Giulia Guerrini, MPharm 07/14/2026

#611: Electrolyte Mythology: Wellness Marketing vs. Evidence - Zoë Rom & Kylee Van Horn 06/30/2026

SNP51: Understanding Blood Glucose Reponses 06/23/2026

#610: Rock, Paper, Salmon – Errors in Interpreting Food Substitution Models 06/16/2026

#609: Unprocessed Red Meat & Cancer Risk 06/09/2026

#608: Performance Nutrition in Elite Rugby – James Morehen, PhD 06/02/2026

#607: Gut Health & Microbiome Testing: What Evidence Do We Actually Have? – Emily Leeming, PhD 05/26/2026

PMOS (PCOS) and Diet: What Can Nutrition Realistically Do? - SNP#50 05/21/2026

#606: Practical Nutrition Strategies for Fat Loss – Luke Hanna 05/19/2026

#605: Fasting, Nutrient Timing & CGMs: Interpreting the Evidence – Prof. James Betts 05/12/2026

#604: How To Interpret Nutrition Research – David Allison, PhD 05/05/2026

#603: Should Dietary Fiber Be Considered Essential? – Andrew Reynolds, PhD 04/28/2026

#602: Avoidant/Restrictive Food Intake Disorder (ARFID) – Megan Hellner, DrPH, RD & Katherine Hill, MD 04/21/2026

#602: Avoidant/Restrictive Food Intake Disorder (ARFID) – Megan Hellner, DrPH, RD & Katherine Hill, MD 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] Interview start [06:23] What is ARFID? DSM-5 definition vs “picky eating” [09:36] Clinical red flags: when restriction becomes a disorder [11:37] ARFID isn’t always underweight: missed cases & diagnostic pitfalls [16:46] ARFID presentation profiles: low interest, sensory sensitivity, fear [18:59] Comorbidities & nutrition consequences [25:16] Evidence-based ARFID treatment [29:16] How to expand foods without pressure [32:28] Weight restoration, stabilization, and long-term maintenance [35:44] What research still needs [38:16] Differential diagnosis & referral Links/Resources (with links to papers and ARFID resources) Subscribe to Join the for free Enroll in the next cohort of our course /episode/index/show/sigmanutrition/id/40150710

#601: Gallstones & Gallbladder Conditions: Impact of Diet – Angela Madden, PhD RD 04/14/2026

#601: Gallstones & Gallbladder Conditions: Impact of Diet – Angela Madden, PhD RD 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] Discussion with Dr. Angela Madden begins [06:53] Understanding the gallbladder [08:08] Gallbladder disorders and their prevalence [13:42] Risk factors and pathophysiology [22:15] Dietary factors and gallstone formation [27:20] Exploring dietary fat and gallstones [34:09] Broader dietary considerations [45:44] Practical dietary recommendations Related Resources Go to Join the for free Subscribe to Enroll in the next cohort of our course Cochrane Review: Related episode: 513: Kidney Stones & Diet – Deepa Kariyawasam, RD /episode/index/show/sigmanutrition/id/40018210

Coevolution With Foods? Multivitamins? Eating Too Early? – Ask Me Anything (SNP49) 04/07/2026

#600: Finite Knowledge, Infinite Ignorance 03/31/2026

#599: Does Unprocessed Red Meat Increase Diabetes Risk? – Gil Carvalho, PhD MD & Mario Kratz, PhD 03/24/2026

#599: Does Unprocessed Red Meat Increase Diabetes Risk? – Gil Carvalho, PhD MD & Mario Kratz, PhD 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] Red meat’s impact is debated [10:54] Mechanisms linking meat to diabetes [15:31] Cohort evidence on diabetes risk [24:43] Differences between cohorts and threshold effects [33:13] RCT evidence and substitution trials [45:49] Why comparator foods matter [50:43] RCT examples and mixed results [01:00:30] Is there cardiovascular risk beyond saturated fat? [01:08:10] Epidemiology patterns and dose thresholds [01:11:36] Personal recommendations and risk tolerance [01:16:19] Key ideas Related Resources (study links, guest bios, additional resources) Join the for free Subscribe to Enroll in the next cohort of our course Mario’s YouTube channel: Gil’s YouTube channel: /episode/index/show/sigmanutrition/id/40384515

#598: How Do Exercise & Diet Interact to Improve Glycaemic Control? – Jenna Gillen, PhD 03/17/2026

#597: Behavioral Psychology in Diet & Health Counselling – David Creel, PhD, RD 03/10/2026

#597: Behavioral Psychology in Diet & Health Counselling – David Creel, PhD, RD 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] Start of interview [05:31] Challenges in nutrition and exercise recommendations [11:01] Behavior change in real-world practice [16:32] Self-monitoring and its importance [23:48] Non-scale victories and positive body image [25:58] Focusing on body capabilities over aesthetics [27:20] Integrating activity into lifestyle [30:30] Exercise snacking and practical tips [33:36] Impact of GLP-1 receptor agonists [38:24] Addressing fear of weight regain [41:24] Effective multidisciplinary obesity treatment Related Resources Join the for free Subscribe to Enroll in the next cohort of our course LinkedIn: X/Twitter: /episode/index/show/sigmanutrition/id/39924990

#596: Why Do Omega-3 Trials Show Mixed Results? 03/03/2026

#595: Neuroplasticity and Reducing Risk of Cognitive Impairment – Dr. Majid Fotuhi 02/24/2026

#595: Neuroplasticity and Reducing Risk of Cognitive Impairment – Dr. Majid Fotuhi 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] Understanding neuroplasticity [05:22] Risk factors for cognitive decline [07:07] Evidence-based interventions for brain health [09:37] The five pillars of brain health [10:42] Dr. Fotuhi’s multimodal program [19:09] Measuring cognitive function [24:43] The role of amyloid and tau in Alzheimer’s [27:53] Genetics and lifestyle in brain health [30:03] Debunking myths and overhyped claims [36:08] Key ideas segment (premium subscribers only) Related Resources (with links to studies mentioned) Join the for free Subscribe to Enroll in the next cohort of our course Dr. Fotuhi’s book: /episode/index/show/sigmanutrition/id/39886150

How Much Dietary Fiber Do We Need to be Healthy? (SNP48) 02/17/2026

#594: Can Muscle Still Adapt Positively When Training Under Low Energy Availability? – Jose Areta, PhD 02/10/2026

#594: Can Muscle Still Adapt Positively When Training Under Low Energy Availability? – Jose Areta, PhD 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] Guest introduction [03:28] Research background and study design [12:18] Study findings: weight loss and endocrine responses [15:47] Muscle adaptations and proteomic analysis [21:47] Interpreting the results: evolutionary and practical implications [26:57] Mitochondrial proteins and muscle adaptation [28:44] Energy deficit as a stressor [34:26] Case study: female tour de france athlete [40:20] Implications for clinical populations [41:44] Future research directions [46:48] Key ideas segment (Premium subcribers only) Related Resources Go to (with links to studies) Join the for free Subscribe to Enroll in the next cohort of our course X: /episode/index/show/sigmanutrition/id/39783330

#593: Can We Define Hyper-Palatable Foods? And Is Processing Actually the Problem? – Tera Fazzino, PhD 02/03/2026

#592: How Much Protein is Actually Healthy? – Eric Helms, PhD & Matt Nagra, ND 01/27/2026

#592: How Much Protein is Actually Healthy? – Eric Helms, PhD & Matt Nagra, ND 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] Discussion starts [07:18] Setting the scene: protein intake and health [09:38] Health outcomes and protein intake [10:27] Mechanistic measures vs. longitudinal outcomes [15:47] The RDA: purpose and limitations [19:19] Higher protein recommendations: where do they come from? [21:48] Protein intake for athletes and general population [27:25] Dose response and optimal protein intake [44:59] Statistical errors in Morton meta-analysis [46:07] Comparing meta-analyses: Morton, Tagawa, and Nunez [56:23] Mechanistic claims and protein intake [59:49] Nitrogen balance and protein requirements [01:11:55] Protein sources and health outcomes [01:18:13] Summarizing optimal protein intake [01:24:31] Key ideas segment (premium subscribers only) Related Resources (with linked studies & resources) Join the for free Subscribe to Enroll in the next cohort of our course Dr. Helms: Instagram: Dr. Nagra: Instagram: /episode/index/show/sigmanutrition/id/39660075

#591: Maintaining Functional Capacity with Age – Brendan Egan, PhD 01/20/2026

#591: Maintaining Functional Capacity with Age – Brendan Egan, PhD 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] Understanding functional capacity [05:56] The importance of muscle strength and mass [14:09] Epidemiology and strength training [25:07] Concurrent training in older adults study [31:05] Barriers to strength training in older adults [34:18] Misconceptions about older adults and exercise [39:13] Exercise snacking and SBAE [51:04] Key ideas segment (Premium-only) Links & Resources (with links to studies) Join the for free Subscribe to Enroll in the next cohort of our course /episode/index/show/sigmanutrition/id/39424430

#590: Is the Nutrient Density of Crops Declining? – Edward Joy, PhD 01/13/2026

Does Processing Really Make Food Unhealthy? (SNP47) 01/06/2026

Does Processing Really Make Food Unhealthy? (SNP47) This is a Premium-exclusive episode of the podcast. To listen to the full episode you need to be subscribed to . 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: Emulsifier-gut interactions Ultra-processing and its effect on food matrix and bioavailability Food liking and hedonic overeating UPFs: Interpreting nutritional epidemiology and RCTs New trial data: the PROMENADE trial, the RESTRUCTURE Trial, etc. In this episode, Alan and Danny review some of the key talking points and their takeaways from this event. Timestamps [00:31] Event overview: processing the evidence [04:44] Conference insights with Dr. Alan Flanagan [07:52] Hypotheses on ultra processed foods [11:53] Microbiome and additives panel [21:51] Food science and technology panel [33:21] Behavioral aspects of food consumption [38:10] Nutritional epidemiology session [47:19] Discussion on dietary pattern classification [50:19] The role of ultra-processed foods in public health policy [54:18] Clinical and metabolic data on processed foods [01:00:55] Critique of the NOVA classification system [01:08:03] Concluding thoughts on ultra-processed foods [01:23:12] Key ideas and methodological standpoints Related Resources Subscribe to Go to Join the for free Enroll in the next cohort of our course /episode/index/show/sigmanutrition/id/39384640

#589: Causal Inference in Nutrition Science – Daniel Ibsen, PhD 12/30/2025

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