#173 - AMA #26: Continuous glucose monitors, zone 2 training, and a framework for interventions

Episode Summary

Executive Summary: This AMA sneak peek centers on how to evaluate CGM use in non-diabetics using a harm-benefit-opportunity-cost framework. Peter Atiyah argues CGMs can provide both insight and behavior change, but may also trigger anxiety or obsession in some people. The episode also previews follow-up questions on fruit-related glucose spikes, sleep wearables, exercise physiology, and cycling.

Main Topics: Framework for evaluating interventions (Priority: 5/5): Peter outlines a general decision framework: assess risk of harm, probability of benefit, and opportunity cost before adopting any intervention. CGM use in non-diabetics (Priority: 5/5): The main discussion applies the framework to continuous glucose monitors, emphasizing that evidence for benefit in non-diabetics is limited but practical value may still exist. Behavior change and accountability (Priority: 4/5): CGMs can function as behavioral tools by increasing awareness and accountability, similar to food logging or being monitored. Risks and contraindications (Priority: 5/5): Potential downsides include anxiety, obsession, and worsening eating-disorder behaviors; some patients should not use CGMs. Opportunity cost and economics (Priority: 4/5): The cost of CGM use is highlighted as a major tradeoff, especially when compared with spending time or money on higher-evidence interventions like sleep, exercise, or meditation. Follow-up questions on glucose and fruit (Priority: 3/5): The episode previews a listener question about why different fruits cause different glucose spikes and whether spike-causing fruits should be avoided. Membership and access logistics (Priority: 2/5): The host explains how listeners can access full AMA episodes and other membership benefits through the subscription program.

Key Arguments: Interventions should be judged by three questions: harm, benefit, and opportunity cost. CGMs likely have low physical risk, but they can increase anxiety or obsessive tracking in some users. For non-diabetics, CGMs may still be useful because they provide insight into carbohydrate tolerance and create behavior change through accountability. Food logging and monitoring often improve choices simply because people know they are being observed. The biggest downside of CGM for many people is not medical harm but cost and the possibility of displacing higher-value habits like sleep, exercise, or meditation. CGM use should be individualized; people with eating-disorder histories are poor candidates. A short trial may be more useful than continuous long-term wear for many non-diabetics. The first months of CGM use are mostly about insight, while later use becomes more about behavior reinforcement and gamification.

Data Points: CGM daily cost: about $10/day - Estimated cost of wearing a CGM continuously Annual CGM cost: about $3,500/year - Derived from daily cost if used every day CGM trial duration: 3 months - Peter suggests most patients deserve a three-month CGM trial Insight vs behavior early in CGM use: 90/10 - Peter says early CGM use is roughly 90% insight and 10% behavior change Insight vs behavior later in CGM use: flips over about 90 days - Behavioral value grows as users learn patterns and extract less new insight Food diary logging frequency: 2 weekdays and 1 weekend day - Example of typical food diary protocol mentioned by the host

Pivotal Quotes: "What is the risk of harm from doing this thing?" — Peter Atiyah: Introduces the first part of his framework for evaluating interventions "I think everybody deserves a three month trial of CGM." — Peter Atiyah: His practical recommendation for most non-diabetic patients "It’s going to start out as about 90, 10, 90% of this is going to be insight... and only 10% of it is going to be changing your behavior" — Peter Atiyah: Describes how CGM value shifts from learning to behavior modification

Implications: Listeners should view CGMs as optional tools, not universal necessities. Their value depends on whether the insight and accountability outweigh cost, anxiety risk, and lost time versus higher-evidence habits.