Shares of Medifast Inc., a maker of weight-loss products, slid 13 percent Wednesday after its acting chief financial officer said he would resign, six weeks after the company’s prior CFO stepped down.

Medifast fell $3.86 to $25.50 in New York, after earlier trading as low as $24.80, in its biggest intraday decline since March 2011. Medifast said earlier in the day that Edward J. Powers would leave as acting CFO and principal accounting officer no later than Jan. 4.

The Owings Mills, Maryland-based company, which sells diet-plan meals and weight-loss counseling, said Powers was leaving “to pursue other interests” without offering further information, according to a regulatory filing. He took over Nov. 13 after Medifast said former CFO Brendan Connors had resigned, citing the same explanation. The shares more than doubled this year through Dec. 24.

Joseph Kelleman, the company’s director of finance-supply chain, will take over as CFO on an interim basis, the company said in its filing. Medifast said it’s continuing a national search for a permanent replacement.

Powers is leaving Medifast to take a job at another company and was always viewed as an interim CFO, Alecia Pulman, a spokeswoman for Medifast, said Wednesday in a telephone interview. She declined to say where Powers was going.