ben greenfield

How Rich Guys Stay Fit, Heart Rate Recovery, Resting Heart Rate Tracking, Heart Rate Variability, Cold Soak Temperatures, Little-Known Pre-Sleep Supplements & Much More With Keith Rabois | Ben Greenfield Fitness

Key Takeaways

  • “You can’t be successful in thinking if your body isn’t healthy and fit.” – Keith Rabois
  • For better body composition, do morning workouts in a fasted state
  • Keep the majority of carbohydrate macros for dinner to have energy & stamina for the morning workout
  • Tips for two-a-day exercise: keep more complex lifts and strength training for afternoon/evening; space workouts around 8 hours apart
  • Heart rate indicators of fitness and recovery: resting heart rate, heart rate variability, two-minute recovery
  • Good sleep is critical! It’s worth the effort to experiment with tools, supplements, devices to optimize
  • The biggest opportunity for innovation is in personalization and tailoring is the biggest area for fitness and health space
  • Most current guidance and technology suffers from the law of averages and doesn’t account for differences in people’s genetics and biology


Keith Rabois (@rabois) is the General Partner at Founders Fund. He has been instrumental in driving five startups from their early stages to successful IPOs and provided seed capital to another ten companies that are currently valued at over $1B, including Airbnb, Lyft, YouTube, Wish, and Yammer.

In this episode, Ben Greenfield and Keith Rabois discuss measuring health through heart rate, a typical workout for Keith, managing sleep, supplements to enhance sleep, exciting things about the future of fitness, and much more!

Host: Ben Greenfield (@bengreenfieldfitness)

The Importance Of Fitness, Health & Nutrition For Success

  • Mental and physical ability lend themselves to each other
  • Early morning workouts can jumpstart the day and get the brain and body going
  • Tip for better body composition: have healthy carbs (most all of daily carb allotment) with dinner and try your morning workout in a fasted state and finish with a cold plunge
  • Note: old lesson of consuming protein consumption within 20 minutes post-workout is essential only if planning another difficult workout within 8 hours
  • “You can’t be successful in thinking if your body isn’t healthy and fit.” – Keith Rabois
  • If you have the time for two-day workouts: keep morning exercises more cardio-based and afternoon/evening workouts more complex and intense strength training
    • Body temperature and nervous system are usually more fired up in the afternoon and can tolerate higher intensity than morning

Heart Rate Measurables

  • Three things to measure related to heart rate: (1) resting heart rate, (2) two-minute recovery, (3) heart rate variability
  • Resting heart rate: a good measure of overall health
  • Heart rate variability: a test of recovery
  • Two-minute recovery: use to optimize training – train intensely and see how fast heart rate recovers
  • To increase two-minute recovery: hill and incline running, stop/start sports like soccer, HIIT (like Barry’s Bootcamp), intense bursts of work
  • Resting heart rate is loosely correlated to two-minute recovery
  • Be sure to include cardio and strength training in exercises
  • Music is important for improving performance and emotional tolerance of exercise
  • High-Intensity Resistance Training (HIRT): alternates between very short bursts of exercise and long recovery; e.g., sprint 10 seconds, recovery 50 seconds – rest and repeat
  • New research suggests HIRT instead of HIIT because heart scaring can occur with too much HIIT that challenges the heart for long durations of time
  • Dose tip: measure total minutes per week in each heart rate zone

Sleep: How To Measure, Optimizing, And Supplements

  • Wrist-worn devices are not accurate in measuring sleep stages (i.e., REM versus non-REM)
  • To measure sleep, Keith uses a headpiece called Zeo and sleeps on an Eight Sleep mattress
  • Try to keep as many devices as possible unplugged or in airplane mode in your bedroom
  • Top three supplements to mitigate effects of device emissions: (1) magnesium; (2) ketones; (3) NAD+
  • Tips for better rest: (1) keep sleep and wake-up schedule consistent, (2) skip the alarm clock if you can, (3) eat dinner a few hours before sleep, (4) keep the room dark or use an eye mask
  • Supplements Keith uses for sleep: Thorne Recovery Pro, magnesium, daily Rozerem (by prescription) to assist with sleep onset
  • Keep melatonin for time travel and time adjustment in new time zone, not for daily use
  • Tools to help induce sleep: eye mask, Apollo, over the ear noise-blocking headphones, and an app called NuCalm

Cold Plunge

  • Cold shifts the body into a state of fat burning because you burn calories to generate heat
  • Cold plunge guidelines: 54 degrees, 8-10 minutes – ideally post-workout
  • If you like your soaks shorter or don’t have time, decrease temperature down to mid-30s
  • Effects on decreased core body temperature linger 12-24 hours and can help with acuity, soreness, sleep

Future Of Fitness Industry

  • Improving sleep has massive benefits and will be a booming field
  • Companies related to areas that extend human lifespan are increasing in prevalence
  • Questions remain around how much interest will remain in home workouts once the pandemic clears
  • Ideal exercise split will likely be a hybrid of gym and home workouts
  • The biggest area for innovation is personalization in health and nutrition – people want specific guidance, i.e., eat this and don’t eat that; do this exercise don’t do that, etc.
  • Current technology suffers from the law of averages and doesn’t account for subtle differences in biology and genetics  
  • No one has developed a great, non-invasive way to personalize health and nutrition information without blood draws or blood collection
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Notes By Maryann

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