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By Ben Harder, Special for USA TODAY For a month that tested her determination, Marilyn Deaton dined on little but fat. The recipes she prepared included eggs baked with gobs of cream cheese, small portions of fish outweighed by butter, oil and mayo, and ground beef mixed with so much heavy cream that it ran a light brown. "I can't stand things that are soft and slimy," says Deaton, 60, of New York. She missed "crunchable stuff," such as carrots, she says. Deaton has Parkinson's disease. The disagreeable diet was an experimental treatment prescribed by her doctors. Four other Parkinson's patients followed the same menu. The results, which included modest improvements in balance, tremors and mood, were encouraging but too preliminary to prove an effect, says Theodore VanItallie of St. Luke?s-Roosevelt Hospital Center in New York. VanItallie and his colleagues published their findings last year in the journal Neurology. Their trial and other recent studies hint that a diet nearly devoid of protein and carbohydrates might temper symptoms of several neurodegenerative disorders, including Alzheimer's and Lou Gehrig's disease, VanItallie says. Researchers suspect that such a high-fat diet also could stall brain tumors and help patients with certain other health problems — if it doesn't cause strokes along the way. Though such a solution may sound far-fetched, a similar diet has been used since the 1920s to treat severe epilepsy. Numerous studies, most of them in children who had exhausted other options, have since found that it reduces seizures. There's scant clinical evidence to address whether the plan, called the ketogenic diet, has wider therapeutic promise. Researchers aren't sure how it works against epilepsy, and they hold various theories about why it might, or might not, help in other disorders. Some of the benefits result from a shift in the brain's metabolism from blood sugar, the body's main fuel, to ketone bodies, a secondary energy source that is a byproduct of fat metabolism, says Richard Veech, a physician and biochemist with the National Institutes of Health in Bethesda, Md. But, Veech says, "while VanItallie has shown that (the ketogenic diet) works, as a practical matter, one can't recommend it." The obvious downside Consequences of high fat intake, heart problems for one, could offset the diet's hypothetical benefits in some people, Veech says. In any case, the daunting challenge of maintaining the unpalatable regimen makes it unlikely to catch on. "Most people would have a very hard time following this diet," says Cathy Non-as, the dietitian at North General Hospital in New York who designed Deaton's plan. The plan requires that 90% of the patients' calories come from fat and just 8% from protein. In the average American diet, fat makes up 33% of calories, and protein accounts for 15%. When a person fasts or subsists mainly on fat, blood sugar declines. The liver responds by converting fatty acids into ketone bodies, which normally circulate in the blood at low levels, rising as time passes since a person's most recent meal, when glucose is abundant. Popular low-carb diets, such as Atkins, may generate some ketone bodies, but not necessarily enough to have a therapeutic benefit, VanItallie says. Ketone bodies can accumulate to dangerous levels, in diabetics, for example, and turn the blood acidic. But moderately elevated levels are theoretically beneficial in a range of circumstances, Veech says. Lab studies and a few desperate medical cases lend some support to that notion. For example, when added to intravenous resuscitation fluids in place of a typical ingredient, ketone bodies also reduce organ damage after major blood loss, says hematologist C. Robert Valeri of the Naval Blood Research Laboratory in Plymouth, Mass. He and his colleagues demonstrated that in pigs. Other teams have shown that the molecules protect mice against neurological changes linked to Parkinson's and Alzheimer's. Last month, researchers at Mount Sinai School of Medicine in New York reported similar findings for Lou Gehrig's disease, or amyotrophic lateral sclerosis. Giulio Pasinetti of Mount Sinai says his team is launching a trial to treat patients with the disease. In an older report, a ketogenic diet appeared to slow tumor growth in two children with inoperable brain cancer. Neurobiologist Thomas Seyfried of Boston College later demonstrated the effectiveness of that approach in mice. Most brain tumor cells, Seyfried says, "can't burn ketones for energy," so elevating ketone levels and simultaneously reducing blood sugar may starve the tumors while nourishing healthy cells. A 'lite' version VanItallie and Non-as are gearing up for a new Parkinson's trial that will test a hybrid of the 90%-fat regimen and the Atkins diet. They've invited their former volunteers to participate. Deaton says her Parkinson's symptoms improved during the original trial, which was conducted in 2003. And losing 26 pounds was a bonus, she says. But even with a more lenient menu on the table, she doesn't plan on signing up again. She's trying a more conventional weight-loss plan. It lets her eat carrots. Posted 5/14/2006 7:56 PM ET ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn