In the late 1950s, Nathan Pritikin was diagnosed with heart disease. Soon after, he adopted a low-fat, high-fibre diet and began a moderate exercise programme. Subsequent medical examinations revealed dramatic improvements in his health. Mr. Pritikin developed the Pritikin Diet Programme based on his experience and opened the first Pritikin Longevity Centre in 1976 so that he could help other people with similar medical problems restore their health.

The Pritikin Diet is almost completely vegetarian, and encourages the consumption of large amounts of whole grains and vegetables. It is high in fibre, low in cholesterol, and extremely low in saturated fat and total fat, containing less than 10 percent of total daily calories from fat. Individuals following the diet are encouraged to eat six or seven meals each day, and are not required to restrict portion sizes. The diet excludes nearly all processed grains and sources of animal protein. In addition to these dietary recommendations, the Pritikin Diet Programme includes regular exercise. Programme participants are required to walk for at least 45 minutes each day.