[4] He holds a Bachelor of Arts summa cum laude in Humanities from the University of Texas at Austin, where he gave the baccalaureate address.

[7] His interest in vegetarian diets began as a college student when he first met Indian yoga guru and religious teacher Swami Satchidananda Saraswati.

[13] Ornish's interactions with Satchidananda eventually led to decades of research beginning in the 1980s on the impact of diet and stress levels on people with heart disease.

It combined diet, meditation, exercise and support groups, and in 1993 became the first non-surgical, non-pharmaceutical therapy for heart disease to qualify for insurance reimbursement.

[14] With the exception of chiropractic care, it was the first alternative medical technique, not taught in traditional medical-school curricula, to gain approval by a major insurance carrier.

[2][15] Ornish worked with the Centers for Medicare and Medicaid Services for 16 years to create a new coverage category called intensive cardiac rehabilitation (ICR), which focuses on comprehensive lifestyle changes.

The Ornish diet is lacto-ovo vegetarian as it includes non-fat dairy products and egg whites in moderation.

[20][21] Critics have stated that Ornish has not provided sufficient clinical evidence to support his claims and his studies have not been replicated.

[23][24] The Ornish diet can lower blood cholesterol but a criticism is that it restricts fish, nuts and olive oil which may protect against heart disease.

[24] Nutritionist Fredrick J. Stare commented that the Ornish diet is too low in fat for most people to follow and it may result in deficiencies of essential fatty acids.