The sprightly fellow sitting opposite me reckons he has, at the very least, 114 years left to live — more than 130 if things really go to plan.

'I'm not actually planning on dying at all,' he explains. 'But you have to pin your life expectancy to something. I don't like saying I'm going to live for ever.'

He is currently 36 years old.

Professor Alex Zhavoronkov is director of the Biogerontology Research Foundation, a UK-based think-tank.

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Live forever: Alex Zhavoronkovm, pictured with Jane Fryer, is a world expert in ageing and biomedical research. He believes he has at least another 114 years to live

He has clean flyaway hair, a brain the size of Jupiter and is a world expert in ageing and biomedical research — an area of study which supports a burgeoning, multi-billion-pound global industry dedicated to longer life and improving the health of the elderly.

He hobnobs with Nobel Prize winners and works tirelessly, both to extend life expectancy and to evangelise about his discoveries — specifically, that medical advances, the widespread use of antibiotics and saying a firm 'no' to marriage and family can transform life expectancy.

In his recent book The Ageless Generation, he claims that if we follow his example and 'reset' our longevity expectations, we can all work and live far, far longer.

Which might sound rather fantastical were it not for the fact that we are all living longer.

Much longer.

This week, Rohit Talwar, a global 'futurist' who advises schools and businesses on how to adapt to change, told delegates at the annual Headmasters' and Headmistresses' Conference in St Andrews that pupils starting secondary school now should expect to live to 120 and work until they are at least 100.

And last week, experts at the World Health Organisation predicted a world in which living to 100 should be the norm.

'These estimates are probably a bit conservative, since it is very likely that people already in their 30s and 40s will be able to work way past 100,' says Alex.

And, he claims, such figures are based on people leaving things to chance — which isn't his style at all.

In his personal quest for eternal life, or at least something approaching it, he uses himself as a laboratory guinea pig for a whole series of experimental drugs, diets and — when it comes to conjugal bliss — lonely deprivations.

Every day he swallows or sniffs more than 100 tested and untested drugs, supplements and vitamins, including aspirin. It must take an age just to pop them all out of their foil strips.

It is very likely that people already in their 30s and 40s will be able to work way past 100 Professor Alex Zhavoronkov

He exercises — yoga, stretching and 100 push-ups, handstands and sit-ups each morning — to protect his muscle mass and skeleton ('very important if you're planning a long life').

And he watches his dietary intake like a hawk. It consists of between 1,600 and 1,700 calories a day, mostly from fruit, vegetables, yoghurt, protein bars, coffee and the occasional cider, which he takes with an anti-diabetes drug to maintain glucose levels.

He also eats some beef, though he believes meat grown in laboratories will be widely available soon: 'It's right around the corner. We're only talking 15 to 20 years.'

In the meantime, he sticks (rather oddly, given all the unhealthy additives) mainly to processed meats and has even been known to have the occasional social cigarette.

Every so often — 'whenever I lose my six-pack' — he methodically starves himself. Between 2004 and 2006 he lived on just 600 calories a day, and his weight fell from 90 kilos to just over 70.

'At that time I was a firm believer that this would result in a better quality of life and life expectancy,' he says.

And did it?

The Latvian scientist asserts that to really live longer we should avoid relationships (file picture). This, he says, acts as distractions to a life lived with the sole intention of lasting an extremely long time

'Not exactly. Those were the two most productive years of my life, because when you're not eating it's harder to sleep, but you can't do much else [for lack of energy] so you have to work. But...'

But?

'I think I damaged my cardiovascular system a little bit,' he says. 'It's not noticeable yet, but I wouldn't recommend anyone fasting for two years. Two days is much better.'

But all this dedicated work is just part of the story.

What has really caused a stir is the Latvian scientist's assertion that to really live longer we should avoid relationships, marriage, children and even material possessions. These, he says, are energy-sapping and act as distractions to a life lived with the sole intention of lasting an extremely long time. At the very least, he says, we should put off such things until we are over 75 or, ideally, over 100.

'Delaying marriage and reproduction is a by-product of shifting your life expectancy horizons,' he says.

When you're planning on living 150 years, marriage is a big decision. You're in for the long term!' Alex

'It would slow me up and distract me from my research. When you're planning on living 150 years, marriage is a big decision. You're in for the long term!'

I ask if he has ever fallen in love.

'How do you classify love?' he asks. 'It's all about chemistry — the so-called 'cuddle' hormone, oxytocin. So, of course, I've been attracted to women, but for me it's more about their intellect and drive, not their looks. But we all have cravings.'

So does he smother his urges completely?

'Oh no! I have sex occasionally, but not on a permanent basis and usually with fellow scientists. Because otherwise — and I'm very sorry for saying it — post-coital interactions can be quite boring.'

We both go a bit pink.

While living to 150 might sound a bit outlandish and not that appealing to some of us, it isn't quite as mad as it seems.

Barely a century ago, life expectancy in the UK was 48 years for boys and 56 for girls. Today the figures are 78.8 and 82.8 years respectively — higher than in the U.S. What's more, our scientific understanding of ageing has been expanding at an even more remarkable rate.

Alex also says that those wishing to live longer should not get married or have children (file picture)

'You only need to have lived through the past 30 years to realise anything is possible,' says Alex. This year, Austrian researchers announced that technological advances in medicine and health have been such that old age now officially starts at 74.

'So living to over 150 isn't unrealistic at all,' Alex continues. 'The current record is 122-and-a-half, and the lady who achieved that didn't exercise. She wasn't even trying, for goodness' sake! Luck — that's the number one factor in ageing.'

But he insists that you can make your own luck, if you follow his simple ten-point plan to longevity.

Some of his suggestions, such as 'think yourself young' (he recommends that septuagenarians play video games to keep their brains limber), socialise with younger people, do your own ageing research and maintain a healthy body, seem straightforward enough.

But others — perform basic genetic testing to assess your susceptibility to diseases, regularly monitor your blood biochemistry to look for changes that could signify health problems, start a personalised preventative drug regimen and store blood and tissue samples for future use — how do we even go about it?

You only need to have lived through the past 30 years to realise anything is possible. Living to over 150 isn't unrealistic at all Alex

'Anyone can do this if they just invest a bit of time, research and money,' he says.

So confident is Alex in his research, he has made a $1 million bet with a fellow longevity scientist about who will live longer. The agreement comes into effect only when they both reach 100.

Meanwhile, he is desperate to spread the word to fellow scientists, the public, his parents and sister ('They were sceptical to start with but now take some of the drugs I do') and the public.

'Yes, I am an evangelist, and if I can get one of your readers to extend their life by just one year by reading about me, then it's worth it,' he says.

He is relentless in his quest. He works 20 hours a day, speaks four languages, lives an itinerant life ('I'm a citizen of the world') and has no truck with holidays.

But does he ever get lonely? Isn't life without relationships, children and the occasional material possession a bit thin?

'Some people are happier working in their basement than socialising over coffee with their friends,' he says. 'As I age, I can develop many more hobbies that will make loneliness obsolete.'

Whatever you think of the lifestyle he has chosen, he does look good on it: no grey hairs ('If I do go grey it will be reversible, like most signs of ageing'), a healthy resting pulse of 55-60 heartbeats a minute and perfect vision (he wears tinted glasses to protect his eyes from ultraviolet light). And always lots of sunblock. 'If you're going out for a sun tan, that's a bad idea for your skin. A very bad idea.'

He also avoids skiing, horseriding and even driving. 'At my age, I have a higher chance of being killed in a car accident than of dying of cancer,' he says. 'I have to be careful.'

For most of us, the prospect of living to 150, hobbling about, squinting, deaf as a post and with bones like balsa wood, isn't that appealing. But Alex has no doubts about his (very long) mission.

'Everyone facing death would give anything for a few more years. Everyone. And in 100 years' time we will be able to augment our bodies with newly programmed cells to keep us younger. I will be in much, much better shape when I'm 130 than I am now!'