Shares of NutriSystem ( NTRI) were gutted Thursday after the diet-products company put third-quarter earnings sharply below its original expectations. The stock recently was down $15.16, or 32%, to $32.41, with more than 15 million shares changing hands by late morning. After the prior session's close, NutriSystem projected third-quarter earnings of 62 cents to 66 cents a share, down from its July forecast of 77 cents to 82 cents. Analysts called for per-share earnings of 82 cents, according to Thomson Financial. The Horsham, Pa., company projected revenue of $188 million, compared with Wall Street's target of $206.7 million. "Our performance with new customers we believe was affected by shorter-term competitive pressures which caused our marketing dollars to become less efficient, resulting in fewer new Direct Business customers than anticipated and customer acquisition costs to be higher than anticipated," said Chairman and CEO Michael Hagan in a statement. Among the competition in the quarter was Alli, a diet drug launched by GlaxoSmithKline ( GSK) in June to much publicity. NutriSystem estimated it had 218,000 new customers in its direct selling business, a 7% decline from year-earlier levels. Thursday's plunge put NutriSystem's stock well below the 52-week low of $40.82 that it hit in February. The stock traded at a 52-week high of $76.20 in December.