In a news release Thursday, Robert Silverman said that his resignation was effective Tuesday. He had served as the firm's president since February 2010, the release said.
The 1-800-GET-THIN campaign had come under increasing scrutiny after the deaths of five Lap-Band patients since 2009.
In December, the Food and Drug Administration sent warning letters to the marketing company and its affiliated surgery centers, saying the ads for Lap-Band weight-loss surgery were misleading because they did not adequately display warnings about risks of the surgery.
The California Department of Insurance also has confirmed it is investigating the surgery centers affiliated with 1-800-GET-THIN for possible insurance fraud. In February, Lap-Band manufacturerAllergan Inc.said it had halted sales of the weight-loss device to all firms affiliated with the marketing company.
In addition to his role as president of 1-800-GET-THIN, Silverman, a lawyer, had represented the firm and its affiliated surgery centers in several lawsuits. He said in an email to The Times that he no longer represents them.
Times staff writer W.J. Hennigan contributed to this report.