NUTRI-BABBLE: I’ll leave DIY DNA tests to genealogy
At the end of January, I embarked on a voyage of DNA discovery aiming to improve my health and fitness, and took a test that promised to provide a bespoke diet and training regime based on my genes.
As I reported back then, DNA-based regimes have become something of a trend, claiming to be the latest and most medically advanced way to get into shape.
I opted for FitnessGenes (£129, fitnessgenes.com), which involved an at-home saliva test and a short questionnaire about my height, weight and activity levels.
Two weeks later, my results were available via their website: information about 48 of my genes; a daily diet plan and a seven-day exercise programme.
DNA-based fitness regimes have become a trendy, ‘medically advanced’ way of getting in shape
The recommendation
All health and lifestyle advice is based on my genetic make-up, they say, with attention given to specific genes responsible for traits such as overeating, fat formation and lactose intolerance.
The advice is very specific: according to my DNA, I need to consume 1,417 calories a day: 178 grams of carbohydrates, 57 grams of protein and 52 grams of fat.
Despite the fact that I am seven-and-a-half stone, which at 5ft 4in gives me a (slightly underweight) BMI of 17.5, my recommended daily intake is 500 calories below that considered sufficient for a moderately active, adult woman.
FitnessGenes say a calorie reduction is necessary because I have two copies of an FTO gene type which puts me at high risk of obesity.
My report also tells me I may be prone to ‘disinhibited’ – that means compulsive – eating.
They say I should follow a low-fat, high-protein diet and manage hunger by drinking lots of water and taking daily doses of glutamine (an amino acid) supplements.
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As for fitness, my presentation of the PGC1A gene, responsible for aerobic capacity, means I would find high-intensity interval training especially beneficial.
If I were to follow the ‘bespoke’ recommendations, I’d indeed lose weight – about two pounds per week, according to NHS choices.
This would mean that within a month, I’d be severely underweight, increasing my risk of osteoporosis, fertility problems and chronic exhaustion.
The expert view
‘Your case is a classic example of why these tests don’t work,’ says geneticist and obesity expert Dr Giles Yeo.
Dr Yeo, who studies ‘fat genes’ at Cambridge University, says: ‘While your FTO expression is partially associated with increased obesity risk, its predictive value is slightly better than flipping a coin. And it’s obvious you’re not overweight.’
But these DNA tests are widely used by geneticists, so surely my results are worth something?
Dr Yeo says: ‘These tests are great for finding out about your genealogy – what percentage Ashkenazi Jew you might be, for example – but that’s about it.’
Dr Dan Reardon, founder and CEO of FitnessGenes, says: ‘The results reflect whichever goal you set, for example weight loss, hence the calorie deficit.
‘BMI is a crude measure of health that doesn’t account for muscle or body-fat percentage. However, we will take your concerns on board and offer extra advice for people at the low weight end of the scale.’
The verdict
I might give the exercise bit a go (I didn’t need a DNA test to tell me that my aversion to the gym might need addressing).
But the ‘cutting-edge’ diet advice? I’ll give it a miss.