Twenty years ago, Peter Attia was working as a trainee surgeon at Johns Hopkins hospital in Baltimore, where he saved countless people facing what he calls “fast death”. “I trained in a very, very violent city,” he tells me. “We were probably averaging 15 or 16 people a day getting shot or stabbed. And, you know, that’s when surgeons can save your life. We’re really good at that.”

What got to him, he says, were the people he treated who were in the midst of dying much more slowly. “All the people with cardiovascular disease, all the people with cancer: we were far less effective at saving those people. We could delay death a little bit, but we weren’t bending the arc of their lives.”

Attia and his colleagues often worked 24-hour shifts, leaving him starved of sleep. When he managed to get some rest, he had an endlessly recurring dream, in which he found himself in the middle of the city, holding a padded basket and staring up at a nearby building. Eggs rained down on him, and though he tried to catch as many as he could, most of them inevitably smashed on the pavement.

The symbolism did not take much decoding: here was all his unease and anxiety about trying to save people who were inexorably moving towards death, but never getting to the source of the problem – the way they lived. “Trying to catch the eggs before they hit the ground seemed far less effective than going up to the roof and taking the basket of eggs away from the guy who was throwing them,” he says. But in the dream, as in life, that part of the story never happened.

In the US, chronic disease is rampant, and recent figures have shown life expectancy is falling; in the UK, there is a similarly depressing picture. But Attia believes it is possible to turn this around. The day we speak, he is at home in Austin, Texas, where it is 11am. Beyond a cup of coffee, he has yet to have any breakfast, but that does not stop him talking for well over an hour about his key vision: increasing people’s “healthspan”, so that they maximise their chances of avoiding disease, and cut down the share of their lives they spend being frail and infirm, perhaps to as little as six months.

Attia, who was born in Toronto, has just turned 50. He is the founder of an Austin-based setup called Early Medical, which introduces its patients to the kind of treatments and lifestyle changes he advocates. He also hosts a weekly podcast called The Peter Attia Drive, whose recent subjects have included the dangers of poor sleep, the history of the cell and the gravity of the US opioid crisis. Last year, he was one of the stars of Limitless, a Disney+ series in which the Australian actor Chris Hemsworth – best known for playing the Marvel superhero Thor – set out on a quest to “combat ageing and discover the full potential of the human body”.

And now there is a book. Outlive, subtitled “the science and art of longevity” is an exhaustive, lucid exploration of Attia’s ideas, created with the help of veteran journalist Bill Gifford. Even if the life changes it describes often seem onerous and complicated, its basic pitch is brazenly simple. We can, Attia says, strike big blows against the “four horsemen” of diabetes, cancer, heart disease and dementia by improving our lives in five “tactical domains”: exercise; “nutritional biochemistry” (ie what and how much we eat); sleep; emotional health; and “exogenous molecules” – or, as they are otherwise known, drugs and supplements.

While what Attia sets out is mostly about how individuals can transform their chances of extending wellness and resilience into old age, it inevitably strays into big questions about how systems of healthcare are organised, and the thinking that drives them.

He divides the historical evolution of illness and treatment into three. What he calls Medicine 1.0 was the shaky way of doing things that humanity relied on for thousands of years: a system based on “direct observation and abetted more or less by pure guesswork”. From the mid-19th century, that model began to give way to Medicine 2.0, which was centred on such innovations as the microscope, the discovery of antibiotics and thorough scientific experiments and research. This is the model we still use, but Attia wants us to move to Medicine 3.0, which “places a far greater emphasis on prevention than treatment”.

What he is proposing has slightly less to do with living longer than people’s quality of existence. “Longevity is such a … I want to say dirty, but it’s such a bastardised term,” he says. “And it just has such a negative connotation. It sort of smells of snake oil and elixirs and, you know, false promises. And what I don’t think gets enough attention is healthspan. Longer lifespan with no improvement in healthspan is a curse, not a blessing.”

Attia is not selling “biological reprogramming technology” – the kind of emerging science that aims at extending life via such techniques as flushing out worn (or “senescent”) cells from the body, or inserting genes into adult cells that convert them into stem cells. In the US, this is attracting no end of private funding, from such enthusiasts as the Amazon founder Jeff Bezos and the tech investor Peter Thiel, who claims to be planning to live to 120. While Attia is “involved with scientists who are doing that type of work”, he says, “it’s amazing to me how many people that I encounter choose to live a relatively unhealthy life today in the belief that that will be their salvation.”

He has really met people like that? “Oh my God: spend more time in Silicon Valley. You know, it’s like these people are spending all of this time and money on these endeavours, and yet they’re not exercising. They’re not sleeping well, and they’re not taking care of their stress, and all these other things that are killing them anyway. But they have this belief: ‘Well, it’s OK, because this thing is going to rescue me.’

“And I say: ‘Look, I’m not going to be the judge of whether that will or won’t rescue you. But let’s incorporate risk management. Let’s think about hedging.’” In other words, rather than placing all your faith in the future of cutting-edge science, it might be a safer bet, if you want to avoid the most trying kind of later-life, to do things that are possible in the here and now.

In the book, Attia writes enthusiastically about Rapamycin, an antifungal agent produced by a soil bacterium first discovered on Easter Island in the south-eastern Pacific. It is commonly used as an immunosuppressant after organ transplant operations, but experiments on animals suggest it may enhance a biological process that slows with age known as autophagy, or cellular recycling – on the face of it, a much simpler potential means of arresting ageing than the kind being funded by Bezos et al. Attia uses it himself at low doses, and has prescribed it to some of his patients. “The most notable side-effect at the doses and frequencies for that purpose are mouth ulcers called aphthous ulcers,” he says. “And they occur in about 10% of people. I’m one of the 10%. So I do get them from time to time, but quite infrequently and usually only in the context of trauma – like if I bite my lip.”

One of his big themes is the kind of genetic screening that can alert people to their susceptibility to life-limiting conditions, so they can take risk-reducing action – something seen in the Hemsworth series, when the actor is confronted with the fact that he is carrying two copies of a gene that make him up to 10 times more likely than most other people to develop Alzheimer’s disease. Hemsworth later hinted that it had played some part in his recent decision to take a break from his profession.

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“It comes down to a philosophy of: ‘Do you or do you not believe that you have some agency over prevention of this disease?’” Attia says. “I think the evidence is quite clear that we have enormous agency over our risk of Alzheimer’s disease and other forms of dementia, including vascular dementia and small vessel dementia. We understand the things that increase risk.”

One good way of pushing that risk down is exercise – and in particular, Attia insists, the activity that even ardent gym-goers often leave to the grunting meat-heads: lifting weights.

“Strength is such an important part of ageing,” he says. “I mean, if you look at the majority of people over the age of 75 and 80, you’ll be so struck by how many activities they can’t do because they lack strength. It can be as simple as: ‘Why can’t most people at a certain age not even get up off the floor?’ They simply don’t have the strength in their hip muscles … The data is unambiguous on this. And when you compare strong with not-strong, the survival difference and the mortality difference is in the order of 200%.”

When it comes to questions about food and eating, Attia’s book is surprisingly noncommittal (“I once believed that diet and nutrition could cure almost all ills, but I no longer feel that strongly about it,” he writes). His key advice is that people should avoid being “overnourished”, which in most cases means reducing their overall energy intake, via a mixture of calorie-watching, restricting certain types of food (eg carbs) and intermittent fasting. The latter comes with a clear warning: that it may be one of the easiest ways to cut calories, but it risks damaging his treasured muscle mass. This leads on to his belief in maximising protein intake, and the benefits of an omnivorous diet.

But what, I wonder, about vegans? “You’re just going to have to work a lot harder and pay attention to amino acid quality,” he says.

Which means? “You’re going to have to go through nutrition labels and say: ‘Am I getting enough lysine and methionine [both amino acids, with a range of health benefits]?’ That’s basically what we do with our patients who don’t eat meat – make sure they’re hitting certain gram targets for each of those.”

Finally, what of sleep? In the book, Attia writes about the long years he spent neglecting it. “Until 10 years ago, yeah,” he says. “Of all the things I write about, that one is probably the one where people are closest to understanding the [correct] point of view. I think that there’s a growing consensus over the past five years that to not sleep is not just a drain on your performance, but also a drain on your health.

“It really makes sense when you consider what an evolutionary sacrifice it was for us to sleep. Think about evolution, and how ruthless it is in optimising your ability to procreate, forage for food and protect yourself – three things you can’t do when you’re sleeping. And yet, somehow, we didn’t out-evolve a way to spend eight hours in an unconscious state. It’s a very compelling evolutionary argument for why this thing must matter.”

When I ask Attia how much it costs to sign up for treatment at Early Medical, he sounds rather coy. “It varies – it’s not a fixed fee. It’s a little more in the first year and then the cost sort of ratchets down because we’re doing more work early on.”

Whatever the wonders of his prescriptions, cynics might picture his clients spending half their lives necking supplements, monitoring their sleep, watching their calorific intake and lifting weights, and conclude that even if you have the time, money and inclination, doesn’t the kind of life he advocates require an impossible amount of work?

“We try to encourage our patients not to go all in and be very extreme out of the gate because what we’re interested in is implementing sustainable changes,” he says. “I always tell them: ‘Look, I don’t want you to be 10 out of 10 for a month and then two out of 10. I’d rather we find out what seven out of 10 is, if you think that that’s what could be maintained indefinitely.’” The point, he says, is to “slowly alter habits one at a time in ways that are somewhat incremental, but that over time compound into significant changes.”

And then there are big social questions. Attia says he believes in the kind of two-tier medical systems whereby everyone has access to a basic level of care, but there are ample opportunities for people with enough money to access the kind of techniques and treatments he offers. But I wonder: as the science advances, won’t that mean those wealthy enough to embrace his kind of thinking running around into their 80s and 90s, while less moneyed people are left to decay – like the kind of society we have now, only more so?

“Your base system has to be preventive and it has to be preventive early,” he says. “And by the way, the most beneficial things that you’re going to do to extend lifespan and healthspan don’t actually cost much money.”

A pause. “Go exercise! How much does it cost to really educate people to exercise? That doesn’t matter how much money you have. Now, I’m not so naive as to think that a single mom who’s working three jobs won’t have less time to exercise. Clearly, there will be gaps in outcomes, but I don’t think those gaps have to be enormous.”

This last thought is left hanging in the air, as he prepares for his first solids of the day. When I ask what he’s having, we return to where we started, with eggs, though this time Attia is in control, and seeking a simple but effective dose of his beloved protein. “An omelette,” he says. “Plain. I don’t put anything in it.”

• Outlive: The Science and Art of Longevity is published by Vermillion (£22). To support the Guardian, buy your copy from bookshop.theguardian.com. Delivery charges may apply