Sego was a US meal replacement diet drink formally marketed by Pet, Inc., (at the time Pet Milk) as Sego Liquid Diet Food. Introduced in 1961^[1] and selling for approximately US25¢ each,^[2] Sego sales registered US$22 million to the company's Milk Products Division by 1965.^[1]

The name Sego derived from a Salt Lake City-based company, Sego Milk Products Company, that Pet Milk had purchased in 1925.^[1]

Sold in 10-ounce cans,^[3] before the advent of aluminum cans or cans with pull tabs, the beverages were available in flavors including Chocolate, Chocolate Coconut, Chocolate Malt, Vanilla, Strawberry, Banana and Orange^[3]—each providing 225 calories (four cans to be consumed daily, for a total of 900 calories).^[4] Marketed under the taglines "See the pounds go with Sego" and "Sego, it's great for your ego," Pet advertised the drinks as being "thicker" and having 10% more protein and 2 more ounces than other 900-calorie foods—e.g., Metrecal, its predecessor in the market and the market leader—asserting that protein "helps control hunger."^[3] In 1966, milk chocolate, caramel fudge and butter pecan flavors became available,^[5] and Pet Milk subsequently offered Sego branded pudding and soup^[6]—and, later still, diet bars.

By 1961, there were more than 100 meal replacement products on the U.S. market,^[6] and Sego competed with such products as Metrecal, and Figurines from Pillsbury,^[6] and was ultimately superseded in the market place by such liquid diet drinks as Slimfast.^{[citation needed]}

In the 2010 book The Hundred Year Diet, author Susan Yager called Sego "baby formula mixed with water and a poor substitute for food."^[6]

Actress Tippi Hedren was discovered by Alfred Hitchcock while shooting a television commercial for Sego on the Today Show.^[7] Hedren later described the spot as "a story line; it wasn't just holding up a product and talking about it. It was a story and apparently he (Hitchcock) saw it."^[8]

• Slimfast
• Metrecal