Libsyn Directory

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

Release Date: 05/05/2026

#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...

#613: Supplement Safety & Medication Interactions – Giulia Guerrini, MPharm

Sigma Nutrition Radio

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...

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

Sigma Nutrition Radio

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...

SNP51: Understanding Blood Glucose Reponses

Sigma Nutrition Radio

This is a Premium-exclusive episode. Go to the Premium feed to listen. Or subscribe to . 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...

#610: Rock, Paper, Salmon – Errors in Interpreting Food Substitution Models

Sigma Nutrition Radio

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...

#609: Unprocessed Red Meat & Cancer Risk

Sigma Nutrition Radio

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...

#608: Performance Nutrition in Elite Rugby – James Morehen, PhD

Sigma Nutrition Radio

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...

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

Sigma Nutrition Radio

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...

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

Sigma Nutrition Radio

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...

#606: Practical Nutrition Strategies for Fat Loss – Luke Hanna

Sigma Nutrition Radio

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...

More Episodes

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:

[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:

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