The latest dope on diet pills is that they may be more dangerous than the Food and Drug Administration has admitted. It wouldn't be the first time the FDA erred on the side of recklessness. Nor would it be the first time that dieters had been disappointed by the promise of quick and easy results. A yet-to-be-released report prepared for Congress by a U.S. Public Health Service physician says that the appetite suppressant in many over-the-counter diet pills is ineffective for most people and can be a health hazard, especially to young people obsessed with thin figures.

The report, by Dr. Paul Raford, raises the possibility of consumer fraud and questions whether the ingredient - phenylpropanolamine hydrochloride, or PPA - should be sold over the counter.The news means that the FDA has some explaining to do. Last month, the FDA had a chance to ban PPA from non-prescription uses but decided not to. Several other non-prescription diet ingredients were prohibited from being sold without prescription, but the FDA declined to put PPA on that list, saying it needed more time to study it. The FDA also allowed PPA to stay in cough and cold remedies.

Raford's study is not so timid. Our associate Scott Sleek obtained an advance copy of the report. PPA, which acts as an appetite suppressant in diet pills, has been linked to heart damage, strokes, seizures and other medical problems, Raford told Congress. PPA is a cousin of methamphetamines, commonly known as "speed" or "uppers." Raford's report says research on PPA, "if further verified, shows potential for massive consumer fraud at best, and at worst could explain the disturbing and increasing incidence of medical malaffect. . . . "

The findings will fuel an ongoing debate over the safety of diet pills. Rep. Ron Wyden, D-Ore., has been spearheading a congressional investigation into the diet industry. And the Federal Trade Commission is investigating claims of the companies that peddle diet pills. An FDA spokesman told us the agency will review the new research. Jessica McDonald put a face on the problem when she recently testified before a congressional subcommittee about her long battle with eating disorders and diets.

A college junior from Washington, D.C., and a dance student, McDonald said she started taking diet pills at age 12. She wanted to lose weight fast, and at one point was popping up to 20 pills at a time. She never saw a doctor or a nutritionist. Raford says the misuse of diet products containing PPA is widespread, especially among people under 30. He said adverse reactions are more common from PPA in diet pills than from PPA in cold and cough remedies. And he said products with PPA result in more reports of adverse reactions than any other leading over-the-counter medicine. Some people compound the risk by "double dosing," using caffeine drinks while taking diet or cold pills.

There are studies that have been kinder to PPA, but congressional investigators say those studies are flawed because they are unpublished, had no peer review, involved small numbers of subjects, did not follow up on their findings and violated research protocols. Most developed nations have banned PPA as a diet aid, and its critics in the United States say that it should be used only under doctor's supervision.