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#588: Menstrual Cycle “Syncing”: Do the Claims Hold Up to Evidence? – Expert Panel

Sigma Nutrition Radio

Release Date: 12/23/2025

#605: Fasting, Nutrient Timing & CGMs: Interpreting the Evidence – Prof. James Betts show art #605: Fasting, Nutrient Timing & CGMs: Interpreting the Evidence – Prof. James Betts

Sigma Nutrition Radio

Fasting, nutrient timing, chrono-nutrition, and continuous glucose monitoring are all topics that have generated substantial interest, but they are also areas where exaggerated claims can easily outpace the underlying evidence. In many cases, tentative hypotheses are presented as if they were already well-established conclusions, despite the fact that the research base is often more mixed and context-dependent than popular narratives imply. It is one thing for an idea to appear biologically coherent. It is another for that idea to translate into meaningful, reliable effects in real-world...

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

Sigma Nutrition Radio

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Sigma Nutrition Radio

Dietary fiber is widely recognized as an important component of a healthy diet, yet it is not typically classified as an essential nutrient. In this episode, Dr. Andrew Reynolds explores whether that distinction still holds, arguing that the traditional criteria used to define essentiality may be outdated when applied to modern nutrition science. The discussion moves beyond simply acknowledging the benefits of fiber and instead examines whether it meets the foundational requirements of an essential nutrient. This includes considering its physiological roles, the body’s inability to...

info_outline #602: Avoidant/Restrictive Food Intake Disorder (ARFID) – Megan Hellner, DrPH, RD & Katherine Hill, MD show art #602: Avoidant/Restrictive Food Intake Disorder (ARFID) – Megan Hellner, DrPH, RD & Katherine Hill, MD

Sigma Nutrition Radio

Avoidant/Restrictive Food Intake Disorder (ARFID) is an eating disorder diagnosis characterized by a persistent restriction or avoidance of food intake that results in clinically significant consequences (medical, nutritional, and/or psychosocial), but without the weight- and shape-driven psychopathology typical of anorexia nervosa and bulimia nervosa. In this episode, Megan Hellner and Katherine Hill outline how ARFID presents across the lifespan, why it is frequently missed in routine healthcare, and what an evidence-informed assessment and treatment pathway can look like in practice. A...

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Sigma Nutrition Radio

This episode examines what we actually know (and importantly, what we do not know) about diet in relation to gallstones and gallbladder conditions. Much of the public-facing guidance around gallstones focuses on “avoiding fatty foods”, yet Dr. Angela Madden explains that this long-standing practice sits on surprisingly weak direct evidence, particularly when judged against the standards typically expected for clinical dietary recommendations. A central theme is the need to separate two distinct questions: dietary factors that influence the risk of developing gallstones (prevention), versus...

info_outline Coevolution With Foods? Multivitamins? Eating Too Early? – Ask Me Anything (SNP49) show art Coevolution With Foods? Multivitamins? Eating Too Early? – Ask Me Anything (SNP49)

Sigma Nutrition Radio

In this episode, Danny answers questions submitted by Premium subscribers. Questions Answered in This Episode: [00:05:13] Is eating too early (relative to chronotype) metabolically problematic? [00:16:55] Can plant-based diets reverse cardiovascular disease? [00:32:54] Are multivitamins useful insurance, or a waste with a good diet? [00:44:56] Does coevolution with foods determine human compatibility and benefit? [00:56:25] How should consumers choose supplement formulations and brands? [01:04:46] Folate vs folic acid: differences and best choice for women of...

info_outline #600: Finite Knowledge, Infinite Ignorance show art #600: Finite Knowledge, Infinite Ignorance

Sigma Nutrition Radio

“The more we learn about the world, and the deeper our learning, the more conscious, specific, and articulate will be our knowledge of what we do not know, our knowledge of our ignorance. For this, indeed, is the main source of our ignorance — the fact that our knowledge can be only finite, while our ignorance must necessarily be infinite.” – Karl Popper To mark Sigma Nutrition’s milestone 600th episode (and 12-year anniversary), Danny and Alan examine several areas in which their views have changed, softened, strengthened, or remained stable over the lifespan of the podcast....

info_outline #599: Does Unprocessed Red Meat Increase Diabetes Risk? – Gil Carvalho, PhD MD & Mario Kratz, PhD show art #599: Does Unprocessed Red Meat Increase Diabetes Risk? – Gil Carvalho, PhD MD & Mario Kratz, PhD

Sigma Nutrition Radio

This episode examines whether unprocessed red meat has a causal role in (1) type 2 diabetes risk and intermediate measures of glucose intolerance (insulin resistance, beta cell dysfunction, glycemic markers) and (2) cardiovascular disease (CVD) risk. While there is commonly observed risk signal from observational cohorts, there exist short-term randomized controlled trials (RCTs) that show largely null effects on glucose homeostasis. This had led to differing opinions and interpretations of the evidence base. Some feel that in the context of an otherwise healthy diet, there isn’t much to...

info_outline #598: How Do Exercise & Diet Interact to Improve Glycaemic Control? – Jenna Gillen, PhD show art #598: How Do Exercise & Diet Interact to Improve Glycaemic Control? – Jenna Gillen, PhD

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...

info_outline #597: Behavioral Psychology in Diet & Health Counselling – David Creel, PhD, RD show art #597: Behavioral Psychology in Diet & Health Counselling – David Creel, PhD, RD

Sigma Nutrition Radio

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...

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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.

Timestamps

  • [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)

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