#604: How To Interpret Nutrition Research – David Allison, PhD
Release Date: 05/05/2026
#622: Body Composition Testing: Methods & Interpretation – Prof. Grant Tinsley
Sigma Nutrition Radio
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....
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#621: Hedonic Overeating, Food Wanting and Impact of Perception – Prof. Graham Finlayson
Sigma Nutrition Radio
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,...
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#620: BPC-157 and Peptide Medications: What Do We Know? – Jordan Feigenbaum, MD
Sigma Nutrition Radio
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...
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#619: How Much Fish Should a Healthy Diet Contain?
Sigma Nutrition Radio
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...
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#618: How Wellness & Optimisation Culture Can Commodify Science – Nick Tiller, PhD
Sigma Nutrition Radio
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...
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#617: What Does Effective Athlete Support Look Like in Practice? – Gemma McGuinness
Sigma Nutrition Radio
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...
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Fiber: Independent Benefits or Just a Proxy for Healthy Foods?
Sigma Nutrition Radio
This episode answers one of the questions raised in the most recent Q&A episode on . The full episode includes the following questions: Fiber: Independent effect or proxy for healthy foods? Exposure frequency for matched dose of red meat MTHFR gene mutations and 5-MTHF Typical fish oil supplements vs pharmaceutical-grade products Health impacts of saturated fat in coconut products Do I need to consume whole grains? Could the increasing use of AI pose a threat to doing rigorous science? To listen to the entire episode (plus the back catalogue of all Premium-exclusive episodes) . For...
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#616: More Testing, Better Health? Harms of Overdiagnosis & Overtreatment - Austin Baraki, MD
Sigma Nutrition Radio
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,...
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#615: Why Processing Doesn’t Determine the Healthfulness of Plant-Based Diets – Alysha Thompson, PhD
Sigma Nutrition Radio
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...
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#614: The Human Skills of Nutrition Coaching – Krista Scott-Dixon, PhD
Sigma Nutrition Radio
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...
info_outlineHow 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:
- [03:30] Interview start
- [06:17] What is true scientific rigor?
- [10:06] Study design and analysis problems in nutrition
- [12:56] The DINS error
- [14:14] Conflation of heterogeneity in response vs. in outcomes
- [17:31] Misunderstanding of p-values and hypothesis testing
- [27:01] Incorrect labelling of “responders” and “non-responders”
- [34:49] Errors related to analysis of secondary outcomes
- [45:01] How can nutrition science improve as a field?
- [51:30] Key ideas segment (Premium-only)
Links:
- Go to episode page (with list of episode resources)
- Subscribe to Sigma Nutrition Premium
- Enroll in the next cohort of our Applied Nutrition Literacy course