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.

• [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

• Subscribe to Sigma Nutrition Premium
• Go to episode page (with links to mentioned studies)
• Join the Sigma email newsletter for free
• Enroll in the next cohort of our Applied Nutrition Literacy course

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.

• [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)

• Go to episode page (with links to studies)
• Join the Sigma email newsletter for free
• Subscribe to Sigma Nutrition Premium
• Enroll in the next cohort of our Applied Nutrition Literacy course
• X: @jlareta

While the term "hyperpalatable" has been used frequently for considerable time to refer to foods that are so appealing and tasty that they drive overeating, this term hasn't been well-defined nor has there been a universal standard for what it means.

One researcher who set out to create an objective definition for hyper-palatable foods (HPFs) is Dr. Tera Fazzino. Using specific defined thresholds of sugar, fat and salt combinations, Dr. Fazzino and colleagues have looked at the impact of consumption of these HPFs.

In this episode, we delve into defining HPFs and their nutrient profiles, whether they have addictive-like properties, how HPFs differ from (and overlap with) ultra-processed foods (UPFs), the mechanisms by which these foods drive overconsumption, and the broader public health implications.

Tera Fazzino, PhD, is an associate professor of psychology at the University of Kansas. Her research focuses on addiction, obesity, and eating-related behaviors.

• [03:39] Interview begins
• [05:05] Attempting to define hyper palatability
• [10:03] Nutrient combinations in hyper palatable foods
• [14:54] Prevalence of hyper palatable foods
• [17:43] Debate on ultra processed foods
• [30:02] Mechanisms behind hyper palatability
• [35:06] Addiction theory and hyper-palatable foods
• [43:38] Early exposure and long-term effects
• [50:53] Key ideas recap

• Go to episode page (with links to studies mentioned)
• Join the Sigma email newsletter for free
• Subscribe to Sigma Nutrition Premium
• Enroll in the next cohort of our Applied Nutrition Literacy course

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.

• [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)

• Go to the episode page (with linked studies & resources)
• Join the Sigma email newsletter for free
• Subscribe to Sigma Nutrition Premium
• Enroll in the next cohort of our Applied Nutrition Literacy course
• Dr. Helms:
  • MASS Research Review
  • Muscle & Strength Pyramids books
  • Instagram: @helms3dmj
• Dr. Nagra:
  • Instagram: @dr.matthewnagra
  • Dr. Nagra's website

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.

• [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)

• Go to episode page (with links to studies)
• Join the Sigma email newsletter for free
• Subscribe to Sigma Nutrition Premium
• Enroll in the next cohort of our Applied Nutrition Literacy course

Nutrient density refers to the concentration of vitamins and minerals in crops relative to their yield. There are widespread claims that today's fruits, vegetables, and grains contain fewer micronutrients than in decades past, often linked to modern farming practices or soil degradation.

This issue is important because if staple crops become less nutritious, it could silently undermine dietary quality and contribute to micronutrient deficiencies ("hidden hunger") in populations.

Dr. Edward Joy is uniquely qualified to address this topic. As a senior research fellow in food systems and nutrition at Rothamsted Research and an associate professor at the London School of Hygiene & Tropical Medicine, his work centers on the intersection of agriculture and nutrition.

In this conversation, Dr. Joy draws on evidence from agronomy and public health to clarify whether the nutrient content of crops has indeed declined, what factors might be responsible (from soil health to plant breeding and climate change), and what we can do to improve the situation.

The discussion emphasizes an evidence-based perspective on soil nutrients, crop varieties, and interventions, cutting through myths to identify real concerns and practical solutions.

• [00:55] Interview
• [04:49] Understanding nutrient density and soil health
• [10:25] Historical evidence and crop experiments
• [20:39] Impact of climate change on crop nutrition
• [24:05] Potential solutions and future research
• [30:34] Translating research to human health

• Go to episode page
• Join the Sigma email newsletter for free
• Subscribe to Sigma Nutrition Premium
• Enroll in the next cohort of our Applied Nutrition Literacy course
• Rothamsted Research
• Dr. Joy's profile page
• X/Twitter:
  • @edward_joy1
  • @NutritionDanny

This is a Premium-exclusive episode of the podcast. To listen to the full episode you need to be subscribed to Sigma Nutrition Premium.

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.

• [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

• Subscribe to Sigma Nutrition Premium
• Go to episode page
• Join the Sigma email newsletter for free
• Enroll in the next cohort of our Applied Nutrition Literacy course

This episode explores how asking better questions and using stronger methods can resolve much of the confusion in nutrition science. Dr. Daniel Ibsen discusses why nutrition research often produces conflicting results and how careful methodological thinking can clarify true diet-disease relationships.

Nutrition science has unique challenges – diets are complex, people self-report their food intake imperfectly, and we can't easily run long-term diet experiments on people. Dr. Ibsen explains how embracing concepts like food substitution analysis, the "target trial" framework, and objective dietary assessment can strengthen evidence.

The episode centers on methodological insights that make nutrition research more reliable and actionable. Key themes include defining dietary comparisons explicitly (the "compared to what?" question), considering people's starting diets, and using causal inference techniques to design better studies.

Daniel B. Ibsen is an epidemiologist and nutritional scientist whose work bridges rigorous causal inference methods with real-world diet and cardiometabolic disease research. He is an Associate Professor at Aarhus University, Denmark.

• [00:13] Introduction to the topic
• [03:23] Interview start
• [08:02] The importance of asking the right questions in nutrition science
• [22:18] Understanding causal inference in nutrition
• [28:58] Challenges and approaches in nutrition epidemiology
• [32:07] Mimicking dietary interventions in studies
• [32:55] Target trial framework
• [39:52] Objective vs. subjective dietary assessment
• [47:01] Why causal effects of ultra-processed foods cannot be identified

• Go to the episode page (with links to mentioned studies)
• Join the Sigma email newsletter for free
• Subscribe to Sigma Nutrition Premium
• Enroll in the next cohort of our Applied Nutrition Literacy course

How much do hormonal fluctuations really influence performance and recovery? Should women be adjusting their training and nutrition based on the menstrual cycle? And do female athletes need different protein strategies or recovery protocols than men?

These are questions that have fuelled countless online claims, from rigid "cycle syncing" programmes to supposedly gender-specific nutrition rules. But how much of that is actually grounded in evidence?

In this episode, the conversation tackles those debates head-on, exploring what we truly know about female physiology, adaptation, and recovery, and where confident narratives outpace the science.

You'll hear from four leading experts: Professors Kirsty Elliot-Sale, Stu Phillips, Shona Halson, and Dr. Eric Helms, as they unpack the data on menstrual-cycle variation, autoregulation, and the real determinants of muscle growth and recovery in women.

These discussions were originally recorded live as part of "The Inside Advantage" event hosted by Optimum Nutrition at the McLaren F1 Performance Centre in the UK, where Danny Lennon moderated the session.

• [02:07] Introducing the topics of discussion
• [07:46] Understanding the menstrual cycle
• [09:22] Recovery and hormonal impact
• [10:23] Where did "cycle syncing" claims originate?
• [15:01] Indirect effects of hormones on performance
• [17:28] Sleep and menstrual cycle
• [18:46] Training adaptations and hormonal differences
• [26:29] Do we have research on female athletes?
• [29:20] Muscle building: are there sex differences?
• [34:01] Do hormones influence training?
• [45:08] Key ideas segment (Premium-only)

• Go to episode page (includes study links, guest bios, & more)
• Join the Sigma email newsletter for free
• Subscribe to Sigma Nutrition Premium
• Watch: Optimum Nutrition's 'Inside Advantage' event
• Previous episodes with these guests: #'s 452, 280, 192, 454

This episode centers on the critical gap in nutrition education within medical training and efforts to bridge it. Guest Akash Patel, a medical student who led a pilot nutrition curriculum, discusses why doctors receive little formal training in nutrition despite poor diet being a major driver of disease. With diet-related conditions (obesity, diabetes, cardiovascular disease, etc.) contributing heavily to morbidity and healthcare costs, the conversation highlights a pivotal push to better equip physicians in nutritional knowledge and counseling.

Patel's work comes at a turning point: there are now calls for standardized nutrition competencies in medical education (e.g., a recent JAMA consensus) and a growing recognition that improving doctors' nutrition literacy could enhance patient care and public trust. But at the same time, medical programs already have a huge workload and little space is available for appropriate training. Others state that nutrition shouldn't fall within the remit of doctors. So how do we reconcile all this?

While this episode focuses on the United States context, the concepts apply to other countries, as it outlines both the challenges and the emerging solutions for closing the nutrition training gap in medicine.

• [03:21] Akash Patel's background and interests
• [05:22] Current state of nutrition education in medical schools
• [07:55] Akash's pilot program and initial findings
• [13:37] Challenges and considerations for curriculum integration
• [15:11] Effective curriculum design for nutrition education
• [23:38] Debating the role of nutrition education in medical training
• [29:00] Practical scenarios and the role of doctors
• [33:58] Advice for implementing nutrition education initiatives
• [38:15] Future directions in nutrition and medicine
• [43:07] Key ideas segment

• Go to episode page (with studies listed & linked)
• Join the Sigma email newsletter for free
• Subscribe to Sigma Nutrition Premium
• Enroll in the next cohort of our Applied Nutrition Literacy course
• Instagram:
  • @withakashpatel
  • @dannylennon_sigma
  • @sigmanutrition