Charles Joseph Genster (September 5, 1917 – August 17, 2010) was an American business executive at the nutrition company Mead Johnson who oversaw the development and marketing of Metrecal, a liquid diet drink that became a weight loss craze in the early 1960s.
While in college he enlisted in the United States Army during World War II and saw action in North Africa and Italy, winning a Silver Star and attained the rank of captain.
The main criticism was taste, with Betty Friedan describing in her 1963 book The Feminine Mystique that women "ate a chalk called Metrecal".
Genster oversaw the addition of chocolate, butterscotch and several other flavors, and created brand extensions such as Metrecal cookies and clam chowder, many of which were first tested on his own children.
In 1963, Peter Wyden wrote in The Overweight Society that "the American consumer made clear that Joe Genster and his teammates had won a hallowed place in the hearts of their countrymen".