I have an unwavering propensity for chocolate Lindt balls - you know, those hard shells of chocolate filled with gooey heaven and individually wrapped like Christmas crackers. Lindt balls, you see, are in my genes.
Recent nutrigenomic research suggests my wishful explanation may not be entirely off the mark. Human beings have around 25 000 genes. As each of us needs to do more or less the same things to stay alive, we share the same basic set. However, our individual genes come in slightly different versions, called gene variants. It's these quirks which give me green eyes while my husband's are piercing blue. Similarly, our gene variants regulate how we expend energy, our appetite and the way our bodies metabolise fat. They can also make us more or less susceptible to chronic conditions such as arthritis, breast cancer and heart disease.

The inescapable maxim of weight loss is that you need to take in fewer calories than you burn. But the big, unanswered question is exactly how best to do it. There's no single answer, primarily because, genetically speaking, our bodies all react differently to diet and exercise. Low-fat may be best for me; a low Gl diet could give you a butt like lessica Biel's. Scientists know that approximately 50 per cent of weight issues (both losses and gains) are genetic. The other 50 per cent is Big Macs, Coke and pork crackling. So you can't blame your flabby arms entirely on your mother.

"Until recently we've only been working with half the equation," explains dietician and nutritional geneticist Yael loffe. "That is, the pork-crackling half. Genetics was the missing link." Now, by bringing genetics into the mix, dieticians can personalise an optimum diet and exercise programme specifically for you. "And when clients have a better response to their weight-loss efforts, they tend to become more compliant to the drag of eating broccoli and skinless chicken breasts," she adds.

WHAT IS NUTRIGENETIC TESTING?
Anybody who's bounced and waddled from Weigh-Less to Atkins to The South Beach Diet to eating only grapes for a fortnight knows that the one-size-fits-all approach to dieting doesn't work. Enter nutrigenomics - the emerging science of personalised, gene-smart nutrition that studies the interaction between genes, diet and lifestyle. By analysing particular gene variants that respond to diet and lifestyle factors, we can determine our responsiveness. The genes tested don't cause disease or obesity by themselves; they simply indicate a susceptibility to a disease or condition. Armed with this knowledge, you can take control of your health. The term nutrigenetic testing suggests presenting yourself at a medical laboratory clutching a still-warm specimen in an old fish-paste jar. In reality, all it takes today is a swipe of your cheek with a sterile swab at home.

THE DNA DIET AND DNA HEALTH

A first for South Africa, DNA Diet and DNA Health were recently launched by lohannesburg-based biotechnology company DNAlysis. They were jointly developed by molecular biologist Dr Daniel Meyersfeld and nutritional geneticist Yael loffe, who is currently doing doctoral research into the genetics of obesity at the University of Cape Town. The DNADiet focuses on optimal weight loss by testing eight genes that impact metabolism and fat loss. Although there are several hundred genes involved in these processes, the specific eight were hand-picked because of the extent of research behind them, explains Meyersfeld. Based on the test results, the client is sent a personal diet plan as well as exercise guidelines. The report includes a three-day sample menu, so even without the help of a dietician, you can design a gene-smart eating plan yourself. DNA Health, on the other hand, aims to optimise health and prevent chronic disease. It focuses on 24 genes which impact on key biological processes, which play a role in the onset of chronic disease. It is not, however, a screening test for inherited disorders. Once you know you've got the potential for a nasty, by avoiding too much fire-blackened red meat, for example, you can combat your genes' potential to derail you. "DNA Health will make people conscious of what is particularly bad for them," explains Meyersfeld.

NOT THE LAST WORD
The DNA Diet is neither a bolt from the blue nor the Holy Grail for porky people. What it is, is a more personal approach to weight loss and health. And no, there's still no escaping leafy green vegetables, fresh fruit and low-fat cheese. Sceptics, particularly from academic quarters, contend that the science of nutrigenomics is not yet advanced enough to offer commercial products. But, as Meyersfeld counters, "There is not one field of medicine where we know everything, but that doesn't stop doctors from using what we do know to help people." "I have no doubt that in a year's time our diet will be based on 15 genes and in the years following maybe 20, then 30," says Joffe. "At present, the worst thing that can happen to you is that you'll eat a healthy diet," she concludes. Worth a try? The fantastic response it's had from dieticians suggests it is. Of course, my test results aren't going to advise me to eat a Lindt ball at least once a day. I can file those under devilish temptations. However, genetic variants make for interesting dinner-table conversation. So interesting in fact, that it's sure to distract others from noticing as you reach out for your second or third delectable Lindt.