ON April 10th the Journal of the American Medical. Association reported that obese women face two to four times the usual risk of having a baby with spinal or brain delects, including spina bifida. This major discovery highlighted yet another hidden cost of obesity, at a time when public health officials warn of a worldwide epidemic of fat. Weight a subject often relegated to the vanity fringe of medical research is now emerging as a key factor in the future health of the species. While increased rates of obesity make that future seem bleak, any hope of reversing the trend is increasingly thought to lie in genetic research and the drugs it may yield.
The rest of the world may be gaining UK rates of overweight and obesity rose to 54 per cent of men and 45 per cent of women between 1980 and 1992 but the US remains the world's fat repository. Last month the Centre for Disease Control and Prevention announced a domestic "epidemic of fat" with one third of the nation's adults categorised as obese that is more than 20 per cent overweight and one half of teenagers significantly overweight. By encouraging problems such as heart disease and diabetes, obesity is related to 300,000 deaths a year in the US, at an annual cost of 52 billion dollars, nearly eight per cent of the nation's overall illness cost.
If the trend continues, it is estimated that the entire US population will be obese by 2030. Reviewing its Healthy People 2000 programme, the Centre for Disease Control and Prevention glumly concluded, "US adults are getting fatter. . . there is no realistic scenario under which the Year 2000 objective will be met." The explanation is straightforward. "Energy storage is part of the body's natural protection against famine," the World Health Organisation reported last month, when it created a global task force on obesity. "When energy storage becomes the rule rather than the exception, it leads to obesity."
In the US, energy storage has become a way of life. Sixty per cent of American adults engage in little or no leisure time activity and only 30 per cent of teenagers exercise vigorously three or more times a week. And Americans at rest are programmed to eat.
A child who watches an average five hours of television on Saturday morning sees 65 junk food commercials, one every five minutes. "We are constantly exhorted to overeat," Theodore Van Itallie, Professor of Medicine at Columbia University recently commented. "Man used to hunt for his food. Now food stalks man."
Not surprisingly, American scientists are in the forefront of obesity research and in January they released apparently miraculous news. After 25 years and $200 million dollars worth of research, a calorie free fat substitute called olestra was approved by the Food and Drug Administration. Tasty, fat free, junk food was at hand.
The 15 billion dollar snack food industry was ecstatic at the implications for its fastest growing segment, the "healthy" snack. Despite warnings by 25 physicians at the Harvard School of Public Health of "side effects that will include increases in cancer, heart disease, stroke and blindness", olestra seemed to promise a nirvana of guilt free over indulgence.
Optimism was reinforced in January when Millenium Pharmaceuticals in Massachusetts identified receptors in the brain that appeared to control how leptin, the so called "fat gene", regulates weight. "The receptor may lead to drugs for potentially the most prevalent form of obesity one resulting from the brain's resistance to leptin rather than lack of leptin," researcher Mark Levin explained. Consequently, Millennium's discovery triggered a race to manufacture oral anti obesity drugs that could for the first time act directly on the receptor.
The potential profit in such discoveries is enormous. The discovery of leptin just 13 months earlier had boosted the biotechnology giant Amgen's stock by $900 million dollars, when the company announced the gene's tendency to strip away body fat when injected into obese mice. "Ideally, the exploitation of this therapeutic strategy would allow patients to eat freely, while the drug simply increased energy utilisation," Dr John Blundell observed in the International Journal of Obesity. "This may be unworkable and unrealistic, given the potent appetite stimulating effect of the commercial environment.
While obese and overweight people hope for an oral remedy in the next five years, and while corporations anticipate their rocketing sales, some commentators question the conclusions being drawn from the genetic findings. Philip Kitcher, a professor of philosophy at the University of California, and author of The Lives To Come The Genetic Revolution and Human Possibilities, lists some of the popular and misleading implications "Fat people should not be blamed for overeating battling bulge is hopeless we can expect hormonal therapies to replace diets we must guard against selective abortion of those with mutations indicating obesity."
Dismissing such "casual gene talk" Professor Kitcher cites as an example increased rates of obesity in lower income groups, which is surely to be understood more in terms of the kinds of food eaten by people in those groups than by the distribution of DNA sequences." African American women, for instance, have twice the obesity rates of white women but they are also twice as likely to live in poverty.
Bruce Spiegelman, a cell biologist at the Dana Farber Cancer Institute, is also sceptical. "Obesity has become epidemic worldwide, while human genes have not changed over 50 or more years," he says. "Clearly genes play some role perhaps analogous to that in drug dependency or sexual orientation but the latest discoveries in no way minimise the environmental and behavioural factors in obesity."
BALANCE the food you eat with physical activity, the US Department of Health advises, in its 1996 Dietary Guidelines. "They encourage people to be moderate and balanced," says Donna Shalala, secretary of health and human services. But do they also reinforce negative stereotypes? "The people who say it is all a matter of self control neglect the chemistry and biology," says Professor Philip James, Chairman of the World Health Organisation's task force on obesity. "They are usually the thin people, who just have the right chemistry."
While public health officials argue over the ideal Body Mass Index, an indirect measure of body fat, sobering research statistics accumulate. Women who gain 20 to 40 pounds after the age of 18 are two and a half times more likely to die of coronary heart disease, a Harvard study found in September 1995. Direct and indirect results of obesity, from depression to diabetes, account for 10 per cent of all sick care visits in Western countries, and the World Health Organisation notes that "in parts of India, Africa, Central and South America, obesity is growing, rapidly in the newly affluent classes.
Psychotherapist Susie Orbach insists that fat is a feminist issue, feminist author Naomi Woolf sees diet plans as patriarchal oppression, and the Network for Size Esteem is one of many groups preaching international "size diversity empowerment." Biologists like Bruce Spiegelman, on the other hand, are relieved to see an urgent medical problem at last being taken seriously by the scientific establishment. "Even five years ago there were no good insights into the scientific aspects of obesity," he remarks, "Perhaps now that the basic genetic pathways are understood, the long term future will be less bleak."
When the World Health Organisation presents the results of its global obesity study next month, however, such optimism may sound hollow.