234 ‒ Chris Hemsworth on Limitless, longevity, and happiness

KEYPOINTS

• 01

  Limitless grew into something more personal than planned.

  Darren Aronofsky called Hemsworth about a six-episode docuseries on longevity. The core team met in New York around November 2019, and shooting began in January. Hemsworth had never hosted anything and worried about seeming genuine. Attia, the show's medical adviser, saw him give more of himself as trust grew. Hemsworth says the risks felt safer once he believed he wouldn't be exploited.

• 02

  A 3–4-day fast is a 'reboot,' but expect to feel rough.

  Attia explains why the fast was four days: three to four days is roughly the point at which the body meaningfully changes how it handles the absence of nutrients. He normally wouldn't take a patient past three days, but production pushed it to four. Hemsworth also worked out daily and learned breath-holding and spearfishing while fasting. Attia warned there would be stretches of sluggish, grouchy mood.

• 03

  Ocean cold is a different stress from an ice bath.

  In Norway the water was about 36°F. Their first swim lasted about four and a half minutes, longer than any ice bath Hemsworth had done, in snow and wind and while treading water, which removes the thin warm layer that forms around a still body in a tub. He says it was more a grit test than adaptation, and he relied on coach Ross Edgley's voice. For comparison, Attia has done long swims at about 49°F and calls even that a huge difference.

• 04

  Joy comes from contrast.

  Attia describes the post-swim euphoria as a 'temporal juxtaposition' of being very low and then very high. We don't feel speed, only acceleration, and he argues emotions work the same way: constant bliss wouldn't feel like profound joy. Hemsworth still makes time for 30–60 seconds of cold water even on busy days.

• 05

  Lift heavy, start early, never stop.

  Hemsworth seems genetically inclined to be muscular and explosive; he says he grew quickly once he started training while playing footy at 17. Attia tells patients that heavy loads recruit fast-twitch (type 2) fibers, which decline with age. The strength episode moved from dragging a car (Edgley had done a similar feat for about 20 hours) to a 100-ft rope climb from a cable car about 1,000 ft above the Blue Mountains, a better test of grip, strength and top-end fitness. Edgley's advice: be strong, not heavy.

• 06

  APOE4/E4 raises Alzheimer's risk sharply but isn't destiny.

  Blood work from December 2019 showed Hemsworth carries two copies of APOE4. Attia puts the risk at roughly 8–10 times the general population. Only about 1% of people carry two copies, and about 20–25% carry at least one. Attia had seen only about three such patients, and two suspected it from family history. He told Hemsworth the gene is not deterministic, that earlier action means more risk reduction, and that it could be 'a blessing' as motivation. Attia calls the view that nothing can be done 'complete nonsense.'

• 07

  Sauna is a passive cardiovascular stressor with consistent, though not fully proven, data.

  In a sauna at about 195°F, Hemsworth's pulse started around 64 bpm. Attia explains that the heart pumps harder to move blood to the skin for cooling, much like exercise. He notes the studies point strongly in the same direction even if the case isn't proven like some interventions. Hemsworth and his wife Elsa have a sauna and ice bath at home, which he calls the best recovery tool.

• 08

  Labeling arousal as excitement changes performance.

  Hemsworth used to feel like throwing up before auditions and could barely think on set. He read about research in which performers had the same physical arousal (raised pulse, clammy hands, shortness of breath) whether they called it fear or excitement. He decided the feeling meant 'Spidey senses up.' He believes fear pushes and purpose pulls, and both are needed. Fear, he says, keeps him self-deprecating and humble.