Kellogg invented a range of exercise equipment for his patients and sought to improve the patients' diet. He developed and patented a variety of new foods including Granola and Corn Flakes, peanut butter, soy milk, and imitation meats. Postcard showing breathing exercises at Battle Creek Sanitarium, circa 1900.

Kellogg's system of “biologic living” advocated vegetarianism, regular exercise, plenty of fresh air and sunshine, drinking 8 to 10 glasses of water a day, and abstinence from alcohol, tobacco, tea, and coffee.

Kellogg was brought up in the Seventh-day Adventist Church from childhood. Selected as a protégé of the Whites and trained as a doctor, Kellogg held a prominent role as a speaker at church meetings.

William Keith Kellogg was born in 1860, eight years after his brother John. There was little love for W.K. in the Kellogg house. His father thought teaching him to read was a waste of time. His mother was cold and distant.