LOS ANGELES — Michele Kessler has been promoted to chief executive of protein bar maker thinkThin, effective Jan. 5. She will succeed founder Lizanne Falsetto, who will remain involved with the company as a board member.

Ms. Kessler has been president of thinkThin since January. She joined the company in October 2013 as chief marketing and innovation officer. During her tenure with thinkThin, Ms. Kessler has spearheaded the company’s first integrated national marketing campaign and has helped launch the company’s most successful new product line-extension with the introduction of thinkThin Lean Protein & Fiber bars.

Prior to joining thinkThin, Ms. Kessler was vice-president of global chocolate strategy and vice-president of chocolate U.S. at Mars. She also spent eight years at Kraft Foods Group where she held senior marketing positions in the biscuit and confections divisions. She began her consumer packaged goods career at Procter & Gamble, where she progressed through assignments of increasing responsibility in the company’s laundry and household cleaning categories.

“When I hired Michele, I knew that her extensive expertise and demonstrated success in growing brands and driving breakthrough innovation was a perfect match for a rapidly growing food company like thinkThin,” Ms. Falsetto said. “I fully expect that her vision, marketing savvy, and passion for innovation for the brand will continue to fuel thinkThin’s market share growth going forward.”

Ms. Falsetto founded thinkThin in 1999, and today the company’s protein bars are among the fastest growing in the category with national distribution across major retailers such as Whole Foods, Trader Joe’s, Kroger, Wal-Mart, Target and Walgreens.