Grace Dent reviews the Up24 - a genius gadget that enthusiastically nags you to get fit

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I’ve been wearing a Jawbone Up 24 for a month. Truthfully, it had lurked, in its package, unloved, on my desk for three whole months before I slid it onto my wrist and downloaded the app. Despite my recent life rennaisance as Just an Everyday Athlete  and my growing obsession with ‘clean eating’ – yes, punch me now - I was strongly adverse to seeing my daily grind transferred to hard statistics.

All these fools, I laughed, traipsing about with their FitBits and Nike Fuel bands tracking footsteps, calories and sleep? It’s like being tagged like a criminal, but for the crimes of ‘neck wobble’ and ‘arse fatness’. Plus, let’s be honest, ‘Fitbit’ is the sort of nickname you might get from a welder you’d snogged in Malaga.

Also, I’d heard these bands are legendarily unreliable. Many years ago an ex bought me a Nike Fuel Band back from America. It malfunctioned and died within three short days of observing me watching back to back Friends re-runs while ordering Singapore Noodles from . Dodgy technology, apparently, although I wasn’t ruling out its suicide.

But, ok, life is different now. I do HIIT  training, I run, I own a stupid dog that loves walking, I’m the sort of tit that eats chia porridge. I slid the comfy black rubber Jawbone onto my wrist, synced it with my iPhone 5 and after five minutes of chatting with it about aims, hopes and dreams, I began to fall in love.

Mr Jawbone - I see him as male, ripped, sparkly of tooth, possibly shouldering a rucksack of rocks - believes I should walk a minimum of 10,000 steps a day. I suspect Mr Jawbone may be Californian as he is relentlessly sunny, and wants me to ‘aim for better’. He bombards me via the app with links to upbeat articles about mindfulness, juicing and happiness. He’s a good guy.

Ok, he’s a slightly annoying guy, but his heart is in the right place. You know that bit in Friends when Monica self-elects as Chandler’s personal trainer and stands by his sofa yelling ‘I’m the energy train! And you’re on board! Choo choo!’? That’s Mr. Jawbone, all the live long day.

So, 10,000 steps. That’s about a six kilometer dog walk and a few trips to the post box and supermarket. Totally doable. He also wants me to sleep eight hours a night. I don’t count calories so I ignore the bit that lets me scan barcodes. I can't help thinking that if you're eating a lot of things with barcodes on, you'll never be healthy anyway.

Quickly, I wanted to please Mr. Jawbone. I craved that electronic cuddle he doles out when I’ve moved 100% of my daily goal.  Or added another activity like swimming or cross training. Or when I've slept eight hours in 24. But the thing is, the moment one hits that goal you'll be asked very politely and amicably, if you dare to try more.

You’ve been to bed at 10pm every night this week! Woo hoo! How about you step this up to Saturday and Sunday too? And you've walked 16.2km a day! Why not beat this goal? ‘But I’d need to give up working and literally walk the streets all day,’ I explained to an inanimate band of black rubber on my wrist. It was almost like it didn’t care.

Of course the darker side to Jawbone addiction is the point when ‘something’ happens, life happens, and one stops exercising altogether. A recent bout of food poisoning left me horizontal for seven days, with the band vibrating every hour to warn me my fitness was going to rot.

Drab messages about my ‘37 steps taken today’ non-accomplishment flashed on my iPhone screen as I lay scanning Twitter for funny cat MPEGs. 'Brilliant. Yet another person in my life I'm disappointing,' I thought sadly. I even informed the band’s mood monitor I was 'sad'. It told me that what would be good for sad was a really long walk.

I’ve lost weight with Jawbone. It’s a motivational kick up the arse. And also, it's stark evidence of the weeks when nothing was achieved at all. Jawbone gives you the actual reason one resembles a Goodyear blimp in a bodycon dress that weekend. Oh, you annoying electronic imaginary man in Lycra. I just can’t quit you.

Jawbone Up24, £124.95, available from  John Lewis