Mind & Matter
Whether food, drugs or ideas, what you consume influences who you become. Learn directly from the best scientists & thinkers alive today about how your mind-body reacts to what you feed it.
The weekly M&M podcast features conversations with the most interesting scientists, thinkers, and technology entrepreneurs alive today.
Not medical advice.
At M&M, we are interested in trying to figure out how things work, not affirming our existing beliefs. We prefer consulting primary rather than secondary sources and independent rather than institutional voices. If we encounter uncomfortable truths or the evidence suggests unfashionable ideas may be valid, so be it.
As the host, my aim is to help you better understand how the body & mind work by curating & synthesizing information in a way that yields science-based insights that you can choose to use or disregard in your own life. Taking ownership of your health starts with taking ownership of your information diet.
I am motivated to connect the dots and distill general principles from what I learn, preferring to ask questions and play devil’s advocate to debating or incessantly pushing my own viewpoint.
My beliefs:
- Taking ownership of your health starts with taking ownership of your information diet.
- All knowledge is provisional and we must work hard to prevent ourselves from becoming attached to our favorite ideas & preferred conclusions.
- Wisdom comes from an iterative, trial-and-error process of learning and unlearning. Letting go of pre-conceived notions can be painful, but pain is information.
Sometimes modern discoveries teach us we must unlearn received wisdom. Other times, modern information overload & historical chauvinism cause us to forget ancient wisdom which stills applies. The framework for learning that I embody is inspired by three Ancient Greek maxims inscribed in the Temple of Apollo at Delphi:
- “Γνῶθι σεαυτόν” (Know thyself)
- “Μηδὲν ἄγαν” (Nothing in excess)
- “Ἐγγύα πάρα δ Ἄτα” (Certainty brings insanity)
Mind & Matter
Nutrition Epidemiology: Fake Science? | John Speakman | 225
Short Summary: The flaws of nutrition epidemiology with Dr. John Speakman
About the guest: John Speakman, PhD is a professor at the University of Aberdeen and runs a lab in Shenzhen, China, focusing on energy balance, obesity, and aging.
Note: Podcast episodes are fully available to paid subscribers on the M&M Substack and everyone on YouTube. Partial versions are available elsewhere. Transcript and other information on Substack.
Episode Summary: Dr. John Speakman explores the pitfalls of nutrition epidemiology, a field that links diet to health outcomes like cancer and obesity but often produces contradictory results. They discuss flawed methods like 24-hour recalls and food frequency questionnaires, which rely on memory and are prone to bias, and introduce Speakman’s new tool using doubly labeled water to screen implausible dietary data. The conversation highlights systematic biases, such as under-reporting by heavier individuals, and emerging technologies like photo diaries and AI for better dietary tracking.
Key Takeaways:
- Nutrition epidemiology studies often contradict each other due to unreliable methods.
- Common techniques like 24-hour recalls & food frequency questionnaires suffer from memory issues, portion size issues, and systematic biases, often underestimating food intake.
- Heavier individuals (higher BMI) under-report food intake more, skewing associations between diet & obesity.
- Speakman’s tool, based on 6,500 doubly labeled water measurements, predicts energy expenditure to flag implausible dietary survey data.
- Emerging technologies, like smartphone photo diaries and AI food identification, promise more accurate dietary tracking than traditional surveys.
- Randomized controlled trials, not surveys, provide the most reliable dietary insights; single-day intake surveys linked to outcomes years later are dubious.
- Speakman advises ignoring most nutrition epidemiology headlines due to their inconsistency and lack of prognostic value for behavior change.
Related episode:
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