Sigma Nutrition Radio

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: [03:50] Dr Austin Baraki's work [06:33] When and why test? [10:36] Probability and context impacts interpretation [14:13] What labs measure [21:15] Specific vs nonspecific symptoms [28:35] Primary vs secondary hypogonadism [32:30] Lifestyle vs TRT decisions [35:21] TRT risks [39:32] Testing timing and variability [41:55] Androgen receptor genetics [44:28] Free vs total testosterone [48:57] Low-normal results: what now? [57:45] TRT risks?: heart and prostate [01:03:55] Side effects and monitoring Links: Go to episode page & resources Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Instagram: @austin_barbellmedicine Barbell Medicine McCormack & Holmes, 2020 – Your results may vary: the imprecision of medical measurements #417: Austin Baraki, MD – What Do Nutrient Blood Tests Actually Tell Us?: Understanding Biomarkers #334: Austin Baraki, MD – Potential Harms of Screening, Overdiagnosis and Overtreatment

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 [04:02] Prof. Finlayson's research [06:06] Food reward [07:13] Liking versus wanting [12:43] Measuring wanting in research [15:27] Does wanting predict overeating? [16:36] Study on hedonic overeating [23:19] Perception and context effects [26:24] Does ultra processing classification add anything? [36:09] Key takeaways and future work [40:35] Premium key ideas Links/Resources: Go to episode page Subscribe to Sigma Nutrition Premium Join the Sigma newsletter for free Enroll in the next cohort of our Applied Nutrition Literacy course Study: Finlayson et al., 2025 – Food-level predictors of self-reported liking and hedonic overeating: Putting ultra-processed foods in context

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 [00:20] Setting out the question at hand [03:26] Overview of typical fish intake recommendations [07:10] Is there good evidence for suggested intakes? [08:10] Historical context [13:22] Key evidence: DART trial and cohort data [19:27] Analysis from Mohan et al. [25:04] Comparator issue: what is fish replacing? [30:52] Fish protein vs. plant protein [44:29] Vegetarian vs. pescatarian cohorts [55:20] Conclusions [01:00:50] Key Ideas segment (Premium-only) Episode Resources Go to episode page (with full study reference list) Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Subscribe to Alan's Alinea Nutrition Education Hub Enroll in the next cohort of our Applied Nutrition Literacy course

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: [02:38] Interview start [03:48] Nutrition beyond performance [10:10] Identity and food choices [18:47] Standards versus perfectionism [24:52] Planning that actually works [28:32] Measuring progress in athletes [33:37] Where discipline can cause problems [38:40] Building high performance environments [45:37] Key ideas (Premium-only) Links: Go to episode page Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Instagram: @gemmcguinnness Verus Performance Davey Nutrition Gemma's Substack

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: [03:35] What screening means [06:36] Choosing what to screen [11:59] Sensitivity and specificity [16:54] Predictive value and prevalence [22:16] Harms of screening and testing [31:02] Overdiagnosis and biases [41:40] The $50,000 physical [44:49] Overdiagnosis vs false positives [53:03] Overtreatment and surveillance [57:22] Clinician action bias [01:02:30] What to screen for Links: Go to episode page (with resources) Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Instagram: @austin_barbellmedicine Twitter: @AustinBaraki

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: [04:23] Interview starts [07:35] Sweetness terms explained [10:17] Sweet liker phenotypes [14:03] Liking vs wanting vs preference [19:18] Trial evidence overview [23:48] Policy and practical impact [30:41] Why we eat foods Links: Go to episode page (incl. links to studies) Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course