Sigma Nutrition Radio

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] Dr. Gillen's research focus
[04:11] Understanding glycemic control
[10:07] Fasted vs. fed state exercise
[11:10] Post-meal exercise benefits
[20:10] Low volume interval training
[26:27] Interval training and blood glucose
[31:29] Energy balance and insulin sensitivity
[36:32] Exercise and nutrition interactions
[40:11] Practical exercise recommendations
[43:56] Key ideas segment (Premium-only)
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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
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LinkedIn: Dr. David Creel
Danny Lennon

X/Twitter: @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] Omega-3 historical context and Inuit studies
[08:38] Mechanisms of omega-3 benefits
[12:49] VITAL and ASCEND trials analysis
[23:41] GISSI-Prevenzione trial insights
[26:44] REDUCE-IT trial and residual risk
[32:19] Significance of baseline triglycerides
[37:57] 2018 Cochrane review
[46:02] Hu et al. meta-analysis
[01:00:27] Practical takeaways for omega-3 supplementation
[01:03:55] Key ideas segment (premium subscribers only)
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Alan Flanagan's Alinea 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] 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)
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Dr. Fotuhi's book: The 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] Addressing the claim "fiber is not an essential nutrient"
[11:23] Carbohydrate quality and fiber
[17:16] Dietary recommendations for fiber
[20:01] Portfolio diet and cardiovascular health
[26:48] Comparing fiber sources
[36:07] Epidemiological evidence on fiber
[41:57] Understanding fiber intake and coronary heart disease
[43:23] Fiber intake and colorectal cancer
[54:06] Diet swap study: south african vs. african american diets
[01:01:47] High fiber diets and diabetes
[01:16:18] Challenges in fiber intake and IBS
[01:21:45] Concluding thoughts on fiber intake
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