He is best known for the invention of the mueslicereal, although his invention differs significantly from what is today known as muesli, and in Switzerland specifically as Bircher Müesli.
Bircher-Benner changed the eating habits of the late 19th century. Instead of much meat and white bread, he postulated eating fruit, vegetables and nuts. His ideas included not only controlled nutrition, but also spartan physical discipline. At his Zürich sanatorium off Bircher-Benner-Platz, the patients had to follow a somewhat monastic daily schedule including early bedtime (21:00), physical training and active gardening work. His theory of life was based on harmony between people and nature. Some of his ideas originate from observing the daily life of shepherds in the Swiss Alps, who lived a simple and healthy life.
In the late 20th century, after closure of the sanatorium, it was briefly a student hostel. It has since been purchased by Zürich Financial Services, and is named the Zürich Development Center. It is used for executive training, and also houses an extensive private art collection.
In parallel to Bircher-Benner in Europe, John Harvey Kellogg worked in the U.S. and followed another similar theory of the healthy diet.