Some commercial diet centers have used the drugs to attract customers.

The F.T.C. is still looking into liquid diet makers and commercial diet centers.

Although the obsession is certainly greatest among young people and in larger cities, diet centers are springing up even in small towns and rural areas.

The diet centers on a "40:30:30" ratio of calories obtained daily from carbohydrates, proteins, and fats, respectively.

"The gyms, the diet center, the plastic surgeons, the cosmetically oriented dermatologists had among their best customers the pretty, never-to-be-olds who lived here."

At one time, the presence of Mr. Roberts at a diet center would have been a rarity.

But disillusionment over dieting can also damage diet centers like Weight Watchers.

And critics say it is in disclosing just such details that diet centers often fall down.

These neurologists may not be at institutions that appear on the published lists of ketogenic diet centers.

For humans, an industry of diet centers, gyms and weight-loss doctors caters to a national obesity epidemic.