Michael Herschel Greger (born October 25, 1972) is an American physician, author, and speaker on public health issues best known for his advocacy of a whole-food, plant-based diet, and his opposition to animal-derived food products.

[4] Greger has said that he was inspired to pursue a career in medicine at the age of nine after witnessing his grandmother's health improvement;[5][6] she attributed to following dietary and lifestyle changes prescribed by American nutritionist Nathan Pritikin.

[9] In 1998, Greger appeared as an expert witness testifying about bovine spongiform encephalopathy when cattle producers unsuccessfully sued Oprah Winfrey for libel over statements she had made about the safety of meat in 1996.

"[21] A decade later, in early 2004, the Daily Bruin, the student newspaper of the University of California, Los Angeles, reported that Greger had called mad cow disease the "plague of the 21st century.

Pfiffner commented that "While much of the book is well supported by research, there are a significant number of fairly questionable claims, leading to a handful of dietary recommendations that seem unnecessary, too restrictive, or potentially counterproductive".

[44] Joseph A. Schwarcz of McGill University argues that although Greger takes his information from respected science journals and produces impressive videos, he has a vegan agenda and cherry picks his data.