I was recently at a drinks party where five middle-aged professionals were having the dreariest conversation it has ever been my social punishment to witness. They were brandishing personal fitness wristbands, while droning on about resting heartbeats, spinning classes, core strength and the cost of gym membership. I've had conversations about baby poo that were more riveting.
The other striking thing about these fitness bores, as they shovelled down canapés and guzzled wine, was that none was particularly svelte.
One looked like Type 2 diabetes was hanging around his back door with a bailiff's order. I was edging away when a financial adviser asked what I did for exercise. I replied that, like AA Milne's Teddy Bear, I get what exercise I can, "by falling off the ottoman". He looked baffled. "But you're thin," said one female lawyer, as if that were a criminal offence. "I don't join the gym, drink Coke or adopt fad diets," I said, wondering if I could market this as a multimillion-pound fitness regime.
For the past few years I've felt like a lone voice on the chaise longue as increasing numbers sign up to health clubs and the total value of the fitness industry spirals ever upwards.
However, as the cardiologist and anti-sugar campaigner Aseem Malhotra has pointed out: "Nearly one in three people alive today is overweight… and no country has lowered its obesity rate since 1980."
No one likes to admit, having spent a small fortune on personal trainers, that they might be better served following author Michael Pollan's mantra: "Eat food. Not too much. Mostly plants."
A study out this week, though, may release a few gym bunnies back into the world.
For it revealed that people who rely on working out to shift excess pounds could well be toiling in vain. It would seem the body adapts to new, more energetic regimes and quite swiftly changes metabolism, meaning fewer calories are burned off.
After a couple of months, gym rats reach a plateau, after which it's hard to shift further flab. This corresponds with Pontzer's research on Tanzanian hunter-gatherers, which demonstrated that they didn't expend far more energy in their wanderings than Western couch potatoes. And of the 300 subjects monitored in the New York study, those with moderate activity levels (ie, those who walked to work and used stairs, rather than lifts) were found to use most calories.
I punched the air in triumph when I read this, as it corresponds exactly to my own notion of an active lifestyle. I have never used a running machine, but few commuters sprint up escalators as swiftly as I do. I hate the expression "hiking", but love a long country walk with a pub at its end.
I can't bear monotonous lengths in public pools, but relish meditational breaststroke in a river, lake or the sea.
The two occasions when I've been cajoled into a gym were pure purgatory. The stale air, clammy with old sweat, is enough to make you heave, while the joyless expressions of the treadmilled masses takes you straight to the gulag.
Worse still is finding yourself a left-footed newbie at the back of a Zumba class, crashing into women who gyrate their pelvises like deranged sexbots from an Austin Powers movie.
All this gym nonsense reaches its climax in January, as people resolve to become healthier in the new year. The tendency has been made worse of late by the no-alcohol fad, Dry January. Who thought up that particular incarnation of Orwellian nightmarishness?
Agreeable nights are dampened by once-witty pals clutching mineral water and gazing mournfully at a ragged slice of lemon. At least with Lent, there's a moral purpose to self-denial; but eschewing alcohol in the bleakest month is heaping misery on desolation - then punishing your friends and family with your sanctimony.
For we all know, the one deed more dastardly than actually doing this stuff is talking about it. And boy does the self-denier like to trumpet it. We know we shouldn't make our bedroom performance a dinner party topic, so why does anyone think it's socially acceptable to drone on about stomach crunches? Women date their personal trainers, then wonder why they're bored into a stupor and fantasising about the compulsive smoker and drinker that is Mad Men's Don Draper.
I don't have a room full of social scientists to throw at the issue, but it's my belief there's a correlation between puritanical regimes and faltering sex lives. Not only are you directing your core energy at anti-hedonistic practices, you're becoming more interested in the way your body looks than the person it feels.
One beautiful friend of mine took up yoga in a big way for seven years and didn't have a single amorous encounter; yet she never made the connection between her body being a temple and the fact that it's not seductive to have sex in a church.
The cheerful fact remains that people who love a drink and lolling about in bed are just so much more alluring than the Health Police.
So were I this nation's health tsar, I'd ban gyms and Dry January and legislate for brisk walking. It would be far better for heart and soul, not to mention dinner party conversation. (© Daily Telegraph)