CHris Hemsworth and Peter Attia sitting inside a sauna

Meet Peter Attia, the Longevity Doctor That Detected Chris Hemsworth’s “Biggest Fear”

An Alzheimer’s gene threatens the actor’s healthspan, but Attia has a plan to fight back.

In the incredible National Geographic docuseries, ‘Limitless’, we get to watch Chris Hemsworth, 39, brave physical and mental challenges in the name of a longer, healthier life. Better healthspan and lifespan is the goal for all of us right? And watching the ‘Thor: Love and Thunder’ actor endure skyscraper heights, plunge into freezing Arctic waters, and muscle up for a 100-foot rope climb is a heart-pounding thrill.

Our hearts skipped several beats, however, when a battery of genetic tests—administered by longevity physician, Dr. Peter Attia—revealed Hemsworth’s “biggest fear”: a very high predisposition for Alzheimer’s disease.

The tests revealed Hemsworth had two copies of the APOE4 gene. According to the National Institute on Aging, only two to three percent of people carry two copies of this gene, which is “the strongest risk factor gene for Alzheimer’s disease” (1). The gene also automatically makes you eight to 10 times more likely to develop Alzheimer’s in the future.

Still, Attia is convinced that with the right lifestyle changes Hemsworth can reduce his risk of Alzheimer’s to that of anyone else.

Who is Attia and what are the best lifestyle changes he advocates for improving healthspan? Here’s everything you need to know.

Attia is a Licensed Medical Doctor

As a longevity doctor, Attia applies the principles of Medicine 3.0 (measures applied based on highly-personalized, evidence-informed guidelines) to his patients with the goal of lengthening their lifespan while simultaneously improving their healthspan.

In times of online degrees and TikTok “doctors,” the term “longevity doctor” may sound unsettling but Attia is legit.

He received his medical degree from the Stanford University School of Medicine and trained for five years at John Hopkins Hospital in general surgery. He went on to spend two years at the National Institutes of Health where he served as a surgical oncology fellow at the National Cancer Institute. While there, his research focused on immune-based therapies for melanoma, which kickstarted his interest in longevity.

His Podcast is Fascinating

Attia hosts a podcast called The Drive, focused on how to maximize longevity through physical, cognitive, and emotional health. Each episode is a deep dive into topics like developments in the field of aging, understanding cardiovascular disease, and understanding sleep and how to improve it. His guests are field-leading doctors, researchers, or other science-based experts—like Rhonda Patrick and David Sinclair—and they always share interesting perspectives and facts.

He’s a Huge Advocate for Preventative Care

The basis of Attia’s practice is preventative care. In an Instagram post, Attia explains why understanding your family history and the context behind that history can help you make informed lifestyle changes like exercise and intermittent fasting to reduce your risk of potential predisposed diseases like cardiovascular disease, dementia, cancer, and metabolic disease.

He’s also big on lab testing. Something we see in action in episode five of Limitless when Attia puts Hemsworth through a full blood panel amongst other tests. On The Drive, Attia lists a series of factors he looks at when testing from genetic precursors like MTHFR and APOE4 to testing for atherosclerosis and cancer. “Metabolic health really matters,” he says. “It is the common thread that links all of these diseases.”

His Book, Outlive, is a Must Read

Attia’s long-awaited brainchild, Outlive: the Science and Art of Longevity is a masterpeice. The 400-page bible of longevity outlines the relationship between healthspan and lifespan and gives solid advice on how to maximize your chances of developing life-shortening disease and cut down how long you spend being frail and infirm as you age.

The book is around his vision of shifting standard practice of care from what he calls “Medicine 2.0,” a reactive approach to medicine that focuses on treating “acute illnesses and injuries,” to “Medicine 3.0.”

“The goal of Medicine 3.0 is not to patch people up and get them out the door, removing their tumors and hoping for the best, but rather to prevent tumors from appearing and spreading in the first place. Or to avoid that first heart attack. Or to divert someone from the path to Alzheimer’s disease,” writes Attia.

He’s a Fan of Extreme Temperature Exposure

In episode two of the series, ‘Shock’, Attia sends Hemsworth into a dry sauna to withstand extreme heat. According to Attia, there are serious benefits of exposure to high temperatures, both hot and cold. Specifically, sauna heat has the best results when endured for at least 20 minutes, four times a week, and north of 180 degrees Fahrenheit.

One study found that sauna use mimics the physiological and protective responses induced during exercise. Repeated sauna use also optimizes stress responses, and protects against cardiovascular and neurodegenerative disease. Most interestingly, it appeared to reduce mortality in a dose-dependent manner (2).

He’s Pro-Fasting…But Not for Everyone

In the show, Hemsworth is eager to find out how changing his eating habits can help in his quest for longevity. Ironically, Attia’s solution is eating no food at all for four long days. Fasting can increase stress resistance and longevity, and decrease the risk of disease, including cancer and obesity (3).

Still, Attia’s opinions on fasting are mixed. On The Drive, he explains fasting is a “tool” that should be used only for the ideal candidate.

That person being someone who either has a good deal of muscle to spare (ahem, Hemsworth) or someone who has over 35 percent body fat and is looking to trim down. That’s because an acute short-term consequence of fasting is a loss of lean muscle mass, which also naturally decreases with age (4).

He Loves Endurance Training

Episode four, centered around strength, finds Hemsworth in the depths of bulking up for Thor: Love and Thunder. He doesn’t just want his muscles to look good, he wants to stay strong and healthy as he grows older in real life.

That’s when Attia reveals that if longevity is his goal, Hemsworth should add endurance training to his routine.

Per Attia, a routine balanced with strength, stability, and endurance training is the key to preparing for the good life at age 100. His ideal endurance regimen involves a blend of zone 2 (low-intensity) training and zone 5 (high-intensity) training. Endurance training builds up our mitochondria (the powerhouse of our cells) content and strength (5). Plus, it fights aging by reducing inflammation (6).

1. Sienski, G. et al (2021). APOE4 disrupts intracellular lipid homeostasis in human iPSC-derived glia.
2. Li, A. et al (2021). Acute and short-term efficacy of sauna treatment on cardiovascular function: A meta-analysis.
3. Cabo, R. et al (2019). Effects of Intermittent Fasting on Health, Aging, and Disease.
4. Tinsley, G. et al (2019). Time-restricted eating and age-related muscle loss.
5. Granata, C. et al (2018). Training-Induced Changes in Mitochondrial Content and Respiratory Function in Human Skeletal Muscle.
6. Rosa, T. et al (2020). Sprint and endurance training in relation to redox balance, inflammatory status and biomarkers of aging in master athletes.