Medifast Inc. agreed to nominate five new board members as part of a deal with activist investor Engaged Capital LLC. The weight-loss and diet products company will nominate Glenn W. Welling, the founder and chief investment officer of Engaged Capital, along with Jeffrey J. Brown, the CEO of Equity Partners LLC, who will become the lead director. Another nominee is Jori Hartwig, the chief operating officer of 3Kintetic Inc. The board restructuring comes as the company closes weight control centers amid a changing market with more competition from technology that helps people follow dieting regimens.