“What Happens When You Track Everything?” — Rob ter Horst on Data, Health, and the Future of Self-Tracking (#11)

Rob ter Horst is a postdoctoral researcher in bioinformatics and the creator behind The Quantified Scientist YouTube channel, where he rigorously tests and reviews health and fitness tracking devices.

Rob shares how his curiosity for data led him from wearing a simple Fitbit to conducting one of the most extensive self-tracking experiments ever — including over 250 weekly brain MRIs since 2018.

We explore his journey into quantifying nearly every aspect of his biology, his insights into the accuracy of popular wearables, the limits of health tracking, and his vision for the future of personalized data and AI-driven health.

Episode breakdown:

00:00 – Introduction to Rob ter Horst — postdoctoral researcher, bioinformatician, and creator of The Quantified Scientist YouTube channel.

01:00 – How Rob’s self-tracking journey began with a Fitbit and evolved into weekly brain MRIs.

03:00 – The world’s most comprehensive personal brain dataset: 250+ MRI scans since 2018.

05:30 – Tracking every aspect of daily life — from mood and microbiome to sleep and cognition.

07:20 – The dream of real-time, actionable feedback from health data (and why we’re not there yet).

08:50 – Rob’s fitness and nutrition goals — weight gain, strength, and balancing cardio with muscle mass.

10:30 – Testing VO₂ max at home and in the lab: insights from metabolic analysis.

12:00 – How hundreds of wearables compare: Apple, Garmin, Oura, Whoop, and 8 Sleep.

15:00 – Health-focused vs. sport-focused vs. smartwatch-first devices — what’s best for you.

17:20 – Continuous glucose monitoring (CGM): usefulness for non-diabetics and the limits of the data.

19:40 – What to measure when your goal is long-term healthspan.

21:00 – How tracking changed Rob’s behavior — especially his sleep.

24:00 – Data-driven fitness: how metrics like heart rate and wattage keep him accountable.

26:30 – Sleep tracking insights: the impact of late meals, workouts, and heart rate variability.

30:00 – Why actionable health algorithms are still far away — and the problem with incomplete data.

31:50 – Rob’s thoughts on AI and the future of health data analysis.

34:00 – Inside his data storage and analysis workflow — from wearables to MRIs.

39:30 – What metrics Rob wishes existed: non-invasive glucose and at-home molecular testing.

41:30 – Inspirations in quantified health — from Peter Attia to Dr. Mike.

43:40 – The fundamentals that matter most: sleep, exercise, and nutrition.

45:30 – Balancing research, YouTube, and the science of self-tracking.

47:00 – Future goals: building a data interpretation platform and expanding testing diversity.

48:30 – What Rob’s most curious about now — Apple’s rumored non-invasive glucose tracking.

49:30 – Closing thoughts and takeaways.

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