''But he can't function with a body fat of less than 4 to 5 percent. The key is education, telling them not to lose too much body fat or too much water. A quick fix is losing water and not body fat.''

Supplements Help, But Is There a Risk?

Questions have arisen since the deaths about whether the use of a popular bodybuilding nutrient, creatine, adds to the hazards of rapid weight loss. Creatine, a combination of amino acids found in skeletal muscles, is popular among athletes in an artificial form that is available in health food stores in powder and capsule form. Wrestlers use it to recover more quickly from workouts and to help develop muscle bulk, but the abuse of creatine without sufficient water intake can cause the body to dangerously overheat.

Bruce Burnett, the national freestyle coach for USA Wrestling, said: ''Creatine retains water in your muscles, so it doesn't work as a coolant. It helps recovery and muscle mass. It's a problem if you take too much and don't follow directions.''

Jones said: ''Creatine is a supplement we use across the board. An athlete who takes it in the morning speeds his recovery for the afternoon. His muscles recover quicker. But if there's a lot of weight loss, don't take it. If you weigh 125 pounds before practice and 119 at the end, that's a 5 percent loss and it's O.K. if you don't dehydrate excessively.''

Jensen, the coach at San Francisco State, agreed that ''creatine is a big thing nowadays.'' He said members of his team used it last season, but ''I told them they needed to get off it.'' A couple of his wrestlers are still on it, including a heavyweight, but Jensen said he does not approve of its use because of concern about possible health risks.

That possibility prompted the F.D.A. investigation. A spokesman for the agency, Arthur Whitmore, told The Associated Press that scientists with the Centers for Disease Control and Prevention ''contacted us with the suspicion that there may be a dietary supplement connection'' in the deaths, but added that there is no evidence yet to suggest that.

Besides diet, the use of rubber suits and heated rooms is also controversial. The National Collegiate Athletic Association's medical guidelines say saunas and rubber suits should be prohibited for weight loss, but the only place they are banned is at the season-ending N.C.A.A. championships. The National Federation of State High School Associations is much tougher, forbidding the use of saunas, sweat boxes, hot showers, whirlpools, rubber, vinyl and plastic suits or similar artificial heating devices and diuretics or other methods of quick weight reduction.