Americans will do almost anything in the world to lose weight except eat less and exercise more. That's why more than 100,000 of us submit our chubby thighs and sagging tummies to the gentle gurglings of liposuction. That's why McDonald's, Procter & Gamble and Monsanto spend tens of millions exploring "fat substitutes" that promise to taste even better than the real thing. That's why the diet industry is now an obese $33-billion-a-year economic juggernaut.
But is technology designed to suck the fat from our food and out of our bodies the best way to go? Or does it really miss the point? After all, we want to eat whatever we want, whenever we want while gaining nary an ounce. Instead of focusing on food and flab, perhaps the real challenge is to redesign the way we digest fatty foods. In other words, rejigger our digestive system in ways that let us eat whatever we want while screening out those noxious lipids.
In fact, we are rapidly acquiring the tools and the knowledge to do just that. Is it crazy to speculate that we might soon be able to, say, genetically re-engineer a tapeworm that could filter out the fat while benignly residing in the intestinal tract? Don't call it "The Parasite Diet." Call it biotech that turns parasites into symbionts.
"It's kind of a joke among people who know tapeworms," says Dr. Scott Halsted, a parasitologist who runs the Rockefeller Foundation's Health Sciences Department, "but it's an interesting idea. There is this dazzling, eye-glazing mania about genetic engineering and what it can do."
Actually, it turns out that tapeworms are probably the wrong parasite for weight management. "There's a lot of mythology surrounding tapeworms," says Dickson Despommier, a Columbia University professor of public health and microbiology. "They don't really induce weight loss; they don't eat enough to compete with our digestive systems for food."
However, Despommier points to \o7 giardia lamblia\f7 as a parasite with potential. A protozoa (basically, a flagellate with an attitude) that's responsible for creating particularly nasty cases of diarrhea, giardia does have one fascinating property: It generates a chemical that prevents the human digestive system from absorbing animal fat.
The trick, says Despommier, would be to figure out giardia's active ingredient and synthesize it. "That would be outstanding," he says. "If you could find out from giardia what its molecular secret was to prevent the absorption of animal fat . . . it's a straightforward logical extension for the biology of this organism."
Theoretically, you could create "anti-fat" pills from this agent or even cultivate specially bred bowel colonies of giardia that block the fat without generating the runs. It's not clear if pharmaceutical companies have begun to explore this parasite's potential--but there's no question that such research would be both technically feasible and possibly enormously profitable.
Just as children with a tendency toward dwarfism are now being offered genetically engineered human growth hormone to boost their height, we might see dangerously obese children offered giardia-based therapies to help them manage their weight. A fat-blocker might be a powerful weapon against arteriosclerosis--one of the most common and crippling heart diseases.
"The idea is provocative," says Lillian Cheung, the director of the Harvard School of Public Health's Nutrition and Fitness Project, "but you would have to proceed with a lot of caution. I would worry that the genetically engineered parasite might also want other things. . . . This would hypothetically be a good idea for research but it must be studied rigorously."
On the other hand, notes Cheung unhappily, "I think this is the sort of thing the public would go for because they look for an easy way out for such a challenging problem." Cheung doesn't expect a Jenny Craig of parasite diets; if the therapy works, she believes these will be parasites by prescription.
There are already plenty of precedents for parasite-driven insights. Understanding the molecular biology of hookworms and leeches has enabled scientists to clone anticoagulants that are critical in treating heart disease. Indeed, says Despommier, who authored "The Worm That Would Be Virus" for Parasitology Today, parasites offer a perverse window into the workings of a variety of human systems. Biotechnology will increasingly enable us to transform the parasite's weapons into medical balms.
Much as the re-engineering of viruses has become essential for gene therapy, the re-engineering of parasites may become essential for therapies ranging from weight-control to heart disease. "They've taken away from us long enough," says Despommier. "It's time they gave back."