Can DNA Testing Really Help You Maximise Your Fitness Levels?

As I stand in the bathroom rubbing a cotton bud-like instrument inside my mouth, my mind floats back to a couple of years ago when a rather swoon-worthy nurse instructed me to swab myself in a toilet at a north London clinic during a routine sexual health check-up. This time round, the test is for something I never thought I'd be investigating: my DNA. And before images of paternity tests start springing to mind, the real reason I'm posting my saliva to the US is to discover more about my health and fitness. DNA tests are all the rage apparently, with a slew of companies promising to analyse your genes and in return offer to help you maximise your fitness.

The aim is to provide people with information about themselves so they can make informed decisions on their health and fitness, says Kate Blanchard, cofounder of US-based biomedical research company Orig3n, which produces DNA kits for everything from nutrition to your skin. “We believe that when people can get direct access to their genetic information, along with insight into how it affects health and behaviour, they can make choices that are right for their own bodies – not what works for someone else.”

So two weeks after posting the swabs off to Orig3n, what did I learn about myself? In my first report, "Fuel", which analyses how your body responds to food and nutrients and is split into four key sections such as food sensitivity and food breakdown, I'm relieved to discover that my lactose tolerance levels are 'normal', as is my alcohol tolerance. I have a 'normal' aversion to coriander, which is a pretty weird thing to find out about, right? I find out I'm 'gifted' at caffeine metabolism – with one of my genes metabolising caffeine four times faster than slow metabolisers, which would be a massive feat if I actually drank the stuff. It feels like a bit of a waste. Why can't I have speed of light metabolism when it comes to loaves of bread? Or Dairy Milk bars?

Later in the report I'm informed that I have a 'normal metabolism', which goes against everything I've ever understood about my body – assuming that not having a super slim physique was somehow attributed to having a slow metabolism. I've actually gone through life telling everyone that I have a slow metabolism (based on no facts whatsoever) and now, apparently, I've been found out. So now I understand nothing. I'm also a little surprised when it informs me that I have the normal gene variant in the 'sweet tooth' category, when I can definitely scoff three caramel slices in one sitting. On the downside, the report flags up that I may have high cholesterol levels and that I'm deficient in vitamin D, and recommends that I boost my sun exposure and eat foods like salmon, tuna and eggs.

The next report, "Fitcode", enlightens me on everything to do with my fitness. It tells me that I have AA genotype, meaning I excel at endurance. Although I do love pounding the buoyant salt water in the Margate tidal pool or cycling along the chalk cliffs of the nearby bays, I think back to my schooldays when I would win the 100-metre race but be a red-faced teenager cursing the cross country track. I also discover that I have fewer fast-twitch muscles, which are responsible for quick movement such as jumping or sudden bursts of energy. Maybe that's my lack of co-ordination explained?

Interestingly, I find that I'm a rare breed; I'm part of just 10% of the population with a gene that has less range of joint motion and less flexible tendons, meaning I'm more prone to injury. Another interesting takeaway is that I tend to recover fast from exercise.

So did I come away feeling enriched with a wealth of information about my body? The opportunity to really dig deep into my health and fitness was definitely fascinating. Some of the results I'm probably never going to think about again (such as being 'gifted' when it comes to vitamin B6 – which I had to google), and as I live a fairly healthy lifestyle I won't be making major diet changes, but I'll follow up on the potentially worrying vitamin D issue, which could go some way to explaining why I'm often tired (and hey, it's another excuse to head to the beach at lunchtime) and I'll look to buy supplements in the winter.

Exercise-wise, I think it just backed up some of what I knew, and as I already do a combination of HIIT, pilates, swimming and weights, I don't think there's anything I'll change. But it was handy to know that I recover fast from exercise so don't need to be too overcautious about hitting the weights the day after a HIIT workout.

However, some critics are sceptical about such tests. “There is real science behind them, but their predictive power is very low,” says Jon Slate, professor of evolutionary genetics at the University of Sheffield. “They don't test an awful lot of genes – the two you took test 24 genes each. Trying to predict somebody's fitness on the basis of 24 or so genes will simply not provide very robust results.”

With "Fuel" and "Fitcode" costing $149 (£115) each, they're not exactly cheap. They might be a way for fitness and health fanatics to step up their game but for everyone else, it may be more cost-effective to listen to your body.