What It’s described as “the only multi-sensor monitor available in the UK that can accurately track calorie burn, physical activity, steps taken and both sleep duration and efficiency”. The latest in weight-loss technology, it can accurately gauge your metabolic rate, that is, calories in, calories out — the core of weight control — and this information, combined with (honest) eating, drinking and weight diaries that you file online, gives a meticulous analysis of your lifestyle.

When 24/7 for 9 days.

Verdict It’s a kind of hell — like having a private detective on your back, or rather, hugging your upper arm, tracking your every move, whether in bed, at the gym, in restaurants, nightclubs or cream-bun shops.

This is embarrassing. Half of my trial period was spent working in New York, where my calorie intake ranged from 1,200 to 3,500 a day. My exercise and sleep regime was equally erratic. One day featured a five-hour walk across Dartmoor and a tower of cheesy crumpets, and I was still heading towards malnutrition. Another day, I ate 2,000 calories more than I burnt. The sleep analysis was the most embarrassing part: I may generally eat well, but I am starved of the most nourishing sleep. (Aren’t we all?)

Ki provided excellent feedback and advice. It’s a great little tool that I could get seriously obsessed with, but, overall, the experience was dispiriting and demotivating.

I don’t really know how to restore balance to my life, and no armband can do that for me. For that I’d need a PA, a shrink or a really controlling other half.

£149.99, plus £9.88 a month subscription; kiperformance.co.uk

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