Want to lose weight? Try eating. That's one of the strategies being
developed by scientists experimenting with foods that trick the body
into feeling full.
At the Institute of Food Research in Norwich, England, food expert
Peter Wilde and colleagues are developing foods that slow down the
digestive system, which then triggers a signal to the brain that
"That fools you into thinking you've eaten far too much when you
really haven't," said Wilde. From his studies on fat digestion, he said
it should be possible to make foods, from bread to yogurts, that make
it easier to diet. While the research is preliminary, Wilde's approach to curbing
appetite is one that some doctors say could be key in combating the
"Being able to switch off appetite would be a big help for people
having trouble losing weight," said Steve Bloom, a professor of
investigative medicine at London's Imperial College, who is not
connected to Wilde's research.
Controlling appetite a challenge
Scientists in North America and elsewhere in Europe are also trying
to control appetite, including through chemical injections or
implantable devices that interfere with the digestive system. Bloom said that regulating appetite through modified foods is theoretically possible. Other mechanisms in the body, like cholesterol production, are already routinely tweaked with medicines.
But Bloom warned that controlling appetite may be more challenging.
"The body has lots of things to prevent its regulatory mechanisms from
being tricked," he said.
For instance, while certain hormones regulate appetite, the brain
also relies on nerve receptors in the stomach to detect the presence of
food and tell it when the stomach is full.
Wilde's research hinges on the body's mechanisms for digesting fat.
Fat normally gets broken down in the first part of the small
intestine. When you eat a high-fat meal, however, the body can only
digest the fat entirely further down in the intestine. That sparks a
release of hormones that suppress appetite.
Wilde's approach copies what happens with a high-fat meal: he coats
fat droplets in foods with modified proteins from plants, so it takes
longer for the enzymes that break down fat to reach it.
That means that the fat isn't digested until it hits the far reaches
of the intestine. At that point, intestinal cells send a signal
telling the brain it's full.
Approach similar to diet drugs
Even though the body hasn't had a high-fat meal, it suppresses the
appetite as if it has. If the fat had been digested earlier in the
intestine, no such signal would be sent. Wilde said the technique should work with any foods that contain fat, like dairy products, pre-cooked sauces, mayonnaise, breads and
pastries, and that taste would probably not be affected.
If all goes well, products could be on shelves within a few years,
he said. In another technique, scientists at the University of Newcastle have
been testing a seaweed extract called alginate that reduces fat absorption by cutting the level of glucose digested by the body before it gets broken down in the large intestine.
That is somewhat similar to how some diet drugs work, such as
orlistat, marketed as Xenical by Roche Holding AG, and Alli by
GlaxoSmithKline PLC. Orlistat blocks fat absorption, but can result in side effects like
gas and diarrhoea. Scientists think that those side effects could be avoided if fibre intake were increased.
In taste tests by several dozen people, participants found that
alginate-enhanced bread tasted as good as or even better than regular
bread, said molecular physiology professor Jeffrey Pearson, who is
leading the Newcastle research.
"It would be very helpful to reduce people's calorific levels by
stealth, so they don't notice there's been a change," Pearson said.
"People don't want to completely change their lifestyle and stop
eating. ... This lets them indulge again."
Concern over control of diet 'magic bullet'
Food companies and pharmaceutical firms are also exploring ways to
tinker with appetite. In 2004, Unilever bought the rights to a South
African plant traditionally chewed by tribesman to ward off hunger.
A small study found that people given the plant extract, hoodia
gordonii, for 15 days, slashed their food intake by 1 000 calories
compared to people on a placebo. A Unilever spokesman said the extract
would be added to a food or beverage and could hit the market within a
Not all experts are convinced appetite-stopping foods will be a
cure-all for obesity. "Humans are a very messy group to control," said Alice H.
Lichtenstein, a nutritionist at Tufts University. People are motivated
to eat for various reasons, from taste to price to childhood nostalgia,
Other experts worry about how such foods might be regulated once
they are available. "If you have this magic bullet, how do you control
who gets it? What do you do about anorexics or female adolescents?"
asked Peter Fryer, a chemical engineer at the University of Birmingham
who also researches modified foods.
But experts agree that foods that cut appetite could be an effective
tool against obesity. "Dieting is an awful bore and most human beings are very gullible,"
Bloom said. "We need all the help science can provide." – (Sapa, October 2008)
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