Seasoned dieters know from experience that not every diet works for everybody.
For every girl who effortlessly drops a stone in a month on the Atkins,
there is another who doesn’t lose an ounce. And while eating low-GI foods is
the weight-loss silver bullet for some people, for others it is just a
recipe for feeling bloated.
Now a new clinic claims it can cut out some of the guesswork with a little
help from genetic science. Simply swab the inside of your cheek with a
cotton bud, send off your DNA to be analysed, and the clinic will point you
in the direction of the diet that will maximise your chances of losing
weight and staying slim. In the USA, DNA dieting is so hot that a
nutrigenomics specialist, who deals with the science of what diet is best
suited to your genes, is the latest lifestyle guru the A list can’t live
without.
The idea that body size is influenced by genetic factors isn’t new, but it is
one that is rapidly gaining momentum, as scientists fill in the blanks about
the 600 or so genes that are thought to influence body size. Gene variations
may offer the only plausible explanation for why two people can eat roughly
the same amount of food, but have vastly different body shapes, say
scientists from Oxford University, who recently discovered that 16% of the
population have inherited two copies of a variant of a gene called FTO,
which makes them 70% more likely to be obese.
Rather than giving fatties a cast-iron excuse to give up dieting for good, the
identifying of fat genes could give people a reason to take healthy-eating
messages on board, thinks Dr Paul Jenkins, a consultant physician at St
Bartholomew’s Hospital, London, and the medical director of a new Harley
Street clinic called Genetic Health. “Our clients say that finding out they
could face obesity in the future gives them the encouragement they need to
be more vigilant about their weight,” he says.
For Allyson Andrews, 39, a corporate public-relations manager for an
international property company, testing positive for several fat genes gave
her the motivation she needed to improve her diet. “I knew I needed to lose
weight, and in some ways learning that I would always find it hard was
depressing,” she says. “But it has also given me renewed enthusiasm for
doing something about it. I’ve joined a gym, and I’m being more careful
about what I eat. Since I got my results three weeks ago, I’ve lost half a
stone.”
DNA dieting is working for people who have tried other diets and failed,
according to the nutritionist Carolyn Katzin, who has designed a six-week
programme for rapid weight loss that is tailored to each client, based on a
genetic screening (www.thednadiet.com). “I find that this additional depth
of understanding about who we are at the molecular level has helped people
to lose weight, and maintain the weight loss, better than any other
approach,” she says. She now has a list of clients who have typically lost
two stone and kept it off for two years.
Genetic Health’s Nutrition Gene test screens for the seven genes it considers
to be the most important in controlling weight. One of them, GNB3, controls
how sensitive your body is to the effects of the hormone insulin, which
plays a crucial role in fat storage. If you have the gene, you are advised
to lower your insulin levels by following a low-GI diet. The NPY gene is
connected to feelings of hunger, and can explain why some people have more
food cravings than others. If you have it, you are advised to eat
low-calorie snacks such as fruit and vegetable sticks at regular intervals,
to keep cravings in check throughout the day. The Beta3 gene influences how
easily you store fat if you are sedentary – it is especially important for
those who have that gene to exercise regularly.
Other genes can be tested to highlight potential health problems if you are
overweight. For example, if you have a particular version of a gene called
plasminogen inhibitor and you are overweight, there is a heightened risk of
inflammation in the body, which has been linked to premature ageing. The
MTHFR gene affects the metabolism of the amino acid homocysteine, high
levels of which have been linked to heart disease. People who have it are
advised to control their homocysteine levels by taking folic-acid
supplements.
Critics of genetic screening say clinics are exploiting a science that is
still in its infancy. “Can a test have any meaning if it looks at just a
handful of the 600 or so genes thought to influence body size?” asks the
nutritionist Dr Sian Astley, a research scientist at the Institute of Food
Research. A previous gene-screening company, Sciona, closed down its UK
operation and relocated to America after criticism from the Human Genetics
Commission. A two-year study by Dr Paula Saukko, at Exeter University, is
looking into whether the public is being misled by DNAdiet claims.
Genetic Health’s chief executive, Brian Whitley, says that clients are made
fully aware of the limitations of the tests before they go ahead. They
receive by post a detailed breakdown of their results, in layman’s language
which they then discuss in a telephone or face-to-face consultation with a
medical director. “We’re staffed entirely by doctors and scientists who have
published 60 papers in the field of hormones and genetic actions on the
body,” Whitley says. “We use only genetic tests that have been well
validated in scientific journals, and we don’t sell clients supplements or
nutrigenomic food products.”
In 20 years’ time, we will all be eating personalised diets, and supermarket
shelves will be stocked with foods designed to counter genetic tendencies,
Astley believes. Until then, she offers an insider’s tip on getting a
personalised diet plan for far less than the price of a gene screen – book a
session with a state-registered dietician through your GP. “Spend an hour
discussing your family history, health and lifestyle,” she says, “and they
will come up with a diet for you that is just as effective.”
More reasons why being fat may not be your fault
Science is discovering that there’s more to staying slim than eating less and
moving more. According to a group of obesity experts, your chances of being
overweight increase if:
- You have an older mother – the odds of a child being obese at the age
of nine increase by 14% for every five-year increase in the age of the
mother.
- You live near heavy industry – industrial pollutants such as
organophosphates and organochlorines, which find their way up the food
chain, can affect your metabolism, activating dormant baby fat cells known
as preadipocytes.
- You have air-con – working in air-conditioned offices saves us calories
that the body would normally use to keep its temperature down. In winter,
the reverse is true, and central heating means we no longer burn off
calories keeping warm.
- You were underweight at birth – small babies who undergo a rapid weight
catch-up are likely to struggle to stay slim when they grow up, as their
bodies adapt to store food, rather than burn it off.
The Nutrition Gene test costs £265, from Genetic Health, 68 Harley Street,
W1; 0870 043 5551, www.genetic-health.co.uk
