Kellogg became a staunch advocate of vegetarianism, believing that a plant-based diet was essential for optimal health and longevity. He promoted vegetarian cuisine at the Sanitarium and in his writings.

Kellogg emphasized the importance of whole grains and fiber in the diet, advocating for the consumption of foods like bran, oats, and corn. This was a radical departure from the processed and refined foods that were becoming increasingly popular at the time.

In addition to diet, Kellogg stressed the importance of hygiene and regular exercise for maintaining good health. He incorporated these principles into the daily routines of patients at the Sanitarium.

Kellogg authored numerous books and articles on health and wellness, including "Plain Facts for Old and Young" and "The Living Temple". He also lectured widely on these topics, reaching a broad audience.

Kellogg's health reform advocacy aligned with the principles of the Progressive Movement, which sought to improve public health and address social problems. He became a prominent figure in the movement and used his platform to advocate for various reforms.

Kellogg's health views weren't without controversy. His advocacy for certain practices, such as enemas, and his restrictive views on sexuality were often criticized and sparked considerable debate.