#103 – Looking back on the first 99 episodes: Strong Convictions, Loosely Held

KEYPOINTS

• 01

  'Strong convictions, loosely held' means trying to shoot down your own hypotheses

  For episode 100, Bob Kaplan interviews Attia about which of his views have changed since the podcast began in mid-2018. Kaplan quotes a blog by Richard Feinman, the SUNY biochemist (not the physicist Feynman), recounting a colleague's description of science: make a hypothesis, then try to shoot yourself down. Changing your mind is 'a feature, not a bug'.

• 02

  Attia stopped taking metformin

  He had taken it since about 2011 for its possible longevity benefits, though few patients in his practice took it. In December 2018, when he started Zone 2 training and checking lactate again, his resting and low-effort lactate was surprisingly high. He concluded that metformin, a weak mitochondrial toxin, was probably blunting his mitochondrial output. He stopped, then spent months experimenting on and off it.

• 03

  Metformin's effect on training is still unclear

  Studies of metformin's effects on muscle mass and training adaptation exist but seem suboptimal, because they often skip functional measures. Attia would like a large study using lactate, Zone 2 efficiency and muscle mass as proxies for whether the drug blunts the benefits of exercise in people without diabetes.

• 04

  Rapamycin took him years to act on

  His interest dates to about 2012, peaked with the December 2014 everolimus paper by Joan Mannick and Lloyd Klickstein, and grew through 2017 interviews with David Sabatini and Matt Kaeberlein. Unlike most drugs, rapamycin has no biomarker to show you're taking enough or too much, beyond side effects such as mouth sores. It took him about four years to settle on a dosing approach, which happened around autumn 2018.

• 05

  Zone 2 came back into his training

  After he stopped time-trial cycling around late 2014 or early 2015, he dropped low-intensity aerobic work entirely, something endurance athletes get without trying, even swimmers training for short events. Now it's a central part of his week. He enjoys it because it isn't hard, and there has never been a day he didn't want to do it.

• 06

  He now sees deadlifts as hugely valuable for longevity, if done properly

  Starting dynamic neuromuscular stabilisation (DNS) about 18 months earlier changed his approach. He lifts lighter than before. He's rarely had 400 lb on the trap bar in the past year, tops out around 350–375 lb, and goes much lighter for slow tempo work. He films every rep of every set and sends it to his coach, Beth Lewis. His warm-up checklist of about 10 exercises takes 10–15 minutes.

• 07

  No more baby aspirin for flights

  He used to assume that aspirin's antiplatelet effect prevented deep vein thrombosis on long flights. On digging, he found little evidence that it does. The gold standard, heparin, is impractical because it has to be injected, so he found supplement alternatives such as one sold as 'Flite Tabs'.

• 08

  Some generic drugs may not be equivalent

  His default through medical school was that generics are identical and brand names a scam. But he has seen patients switched from Crestor to generic rosuvastatin show no change in their labs after two months, despite adherence they had no reason to lie about. Katherine Eban's episode (#71) on generic drug manufacturing shifted his view; he calls it one of the 10 most important episodes.

• 09

  He would push omega-3 levels higher

  Before Bill Harris's episode, Attia targeted a red-blood-cell omega-3 index of about 8–10%. Afterwards he felt 12–14% could be reached without side effects and with more benefit. He says clinical trial data on EPA and DHA are still unclear, including a setback in a recent EPA-plus-DHA trial.

• 10

  Omega-6 associations are confounded

  Foods high in omega-6 polyunsaturated fat are often 'crap', which makes associations hard to interpret. He calls it a polarising topic worth a deep dive. It matters little for his own diet but has big public-health implications.