IT BORDERS on heresy to say it, but whether you join the estimated one in four adults in Ireland who is obese or not is influenced in no small part by your genes.
That's according to leading nutrition researcher Prof Mike Gibney, director of the new Institute of Food and Health at University College Dublin, which was launched last week.
"We live in an environment which is obesogenic, there's an excess of cheap food. And, without doubt, the evidence coming along says the reason why some people get fatter faster is their genes. End of story," says Gibney, who is professor of food and health at UCD and a co-ordinator of the five-year pan-European Lipgene project, which looked at links between human genes, diet and health.
"At a typical nutrition society meeting they will say obesity is a huge social gradient and they will show you statistics: 12 per cent of male professional workers in the UK are obese, and 19 per cent of male manual workers are obese. So there's a big difference. Why is that?
"You can go down the road of lack of education and money, the schools and factories serve junk food, they live in food deserts so there are no decent shops around them selling fruit and vegetables. All the usual answers."
But Gibney prefers to turn the statistics on their head and look at the majority numbers of people who are not obese despite living in the same environment as those who are.
"The statistics also mean that 88 per cent of male professionals and 81 per cent of male manual workers are not obese. Why? Did their schools and factories not serve junk food? Are they living in a food desert but they happen to know where there is an oasis? It just doesn't stack up."
A more plausible answer is emerging from studies on identical and fraternal twins, according to Gibney, which can dissect out the effects of genes and the environment.
"What they are finding is that obesity has a heritability of 80 per cent," he explains. "So it's higher than Alzheimer's disease, depression or osteoporosis, it's one of the most heritable conditions going."
In particular, studies are finding that identical twins show huge overlap in their taste preferences, the rate at which they eat and when they feel full, says Prof Gibney.
"There's a whole area now looking at why do people make the food choices they do, and it's not because they are ignorant or poorly educated. Of course that's important, but genetics comes into it as well. So genetics is definitely going to be the dominant thing over the next 10 or 20 years."
Parading genes as a contributor to obesity isn't always a popular option, because it could tempt people away from controlling their diets, notes Gibney. "When I raise this issue at international conferences I nearly get shoes thrown at me," he says. "It is the greatest heresy to say it's your genes, because then people can throw up their hands and say it has nothing to do with me, it's my genes.
"Even though you can do something about it."
But recognising the genetic component could bring huge benefits, such as helping identify the people most at risk of developing obesity, says Gibney. "For sure there is the danger that people will cop out, but knowing the genetics can help us predict the problems," he says. "And I think if we can find out who exactly is most likely to be sensitive to the obesogenic environment, that's going to be an easier battle to fight."
Understanding the genetics of obesity could ultimately point the way to more effective interventions, he adds. "It may well be that in the course of time, parallel to the genetic developments there may be drug developments that help us to control appetite, and it may be that you can't give that to everyone because it's too expensive.
"So you could say we will target someone because they carry several genes and that gene we know is likely to increase [body mass] by 4kg, and that gene by 2kg. I think it will be that specific."
Looking at the consequences of exposing genes to an obesity-promoting lifestyle will also help discover new markers of disease in the blood, says Gibney. "We will be able to use more complicated markers than we have at the moment."
On the non-food side of the obesity equation, Gibney wants to make the built environment less sedentary, and this is an area of study for the new institute, which consolidates core research in agriculture, food processing, safety, consumer and regulation issues and how nutrition affects our health.
"Physical activity is absolutely vital. Without physical activity we are all kidding ourselves, and there should be simple things we can do in an office environment to improve that activity," he says.
"I should be able to press a button and bring a desk up so that at least I stand. We have a meeting bike - eight people sit on it, they all pedal, one person steers and has the brakes. And there's no reason why there shouldn't be a physical activity room available."
And moving from the extra footprints we do want to the kind we don't, UCD research is also looking at the carbon cost of the Irish diet, including the impact of our exports and imports.
"There are a lot of inaccurate data around the world but we want to try to get something that is accurate for the Irish diet. That's a long-term investment," says Gibney.
He also foresees that thanks to food regulation, consumers will see more rigorous science standing behind claims made for the products they buy.
"The marketing people have had a decade of good fun, of coming up with spin stories, sometimes based on very solid science but I'm afraid often based on 'it looks like this' and a spin put on it. And I would be glad to see that day go. It will mean a better level of science going in."
