DENVER — The Simply Good Foods Co., a developer and marketer of nutritional foods and snacks under the Atkins and Simply Protein brands, has agreed to acquire Quest Nutrition, L.L.C., El Segundo, Calif., for $1 billion in cash, or approximately $870 million, net of tax benefits, on a cash-free and debt-free basis.

Quest Nutrition manufactures and markets a range of products under the Quest brand, including protein bars, protein cookies, protein powders, protein chips and frozen pizzas. Quest has net sales of $345 million and adjusted EBITDA of $50 million, and the combined businesses generate an estimated $800 million in net sales and have strong operating margins, according to Simply Good Foods.

“The acquisition of Quest strengthens Simply Good Foods’ position within the nutritional snacking category by expanding our portfolio of brands and product offerings while also providing us with greater consumer and channel diversification,” said Joseph E. Scalzo, president and chief executive officer of Simply Good Foods. “This combination delivers on our strategy to become a broader nutritional snacking company that offers consumers a broad range of brands and products that satisfy their nutritional needs. We also believe that our collective brands will benefit from increased cross-selling and marketing opportunities, as well as enhanced go-to-market strategies that will drive meaningful net sales and earnings growth.

“Quest is supported by an innovative spirit and dedicated employees committed to supporting consumers’ healthy lifestyles, and both Quest and our existing brands will benefit from sharing best practices and insights in marketing, distribution and supply chain management to deliver on our commitment to customers and consumers.”

David W. Ritterbush, president and c.e.o. of Quest Nutrition, will join the Simply Good Foods board of directors upon the closing of the transaction, which is expected to occur by the end of the year and is subject to the satisfaction of customary closing conditions and regulatory clearance.

“We are excited to join the Simply Good Foods family, and I’m personally pleased to be joining the Simply Good Foods board of directors upon closing, as we collectively drive the next stage of Quest’s growth,” Mr. Ritterbush said. “The Simply Good Foods team has a strong track record in building leading nutrition brands, and I feel that Quest will fit perfectly in their overall mission. As part of Simply Good Foods, Quest will benefit from the combination of two great organizations focused on providing consumers with healthier food choices. I’m incredibly proud of everything that Quest and our team has accomplished and excited for the next phase of our growth by joining a larger, more diverse nutritional snacking company.”

Simply Good Foods expects to benefit from Quest’s effectiveness in e-commerce and social platforms and non-tracked distribution channels, while Quest is expected to benefit from Simply Good Foods’ expertise in traditional media and building distribution in food, drug and mass channels. The companies expect to achieve an estimated $20 million in cost synergies over three years through efficiencies of scale.