[2] The diet rejects all animal products as well as cooking oils, processed food, alcoholic beverages and caffeinated drinks.

[6][7] In 2016, he was one of four named plaintiffs in a lawsuit by the PCRM alleging improper influence by the egg industry on establishing cholesterol recommendations in the US.

[3] It is based on a variety of starches such as rice, potatoes, corn, breads, pasta with fresh or frozen fruits and vegetables.

[13] His book The McDougall Plan was on New York Times paperback "Advice, How-to, and Miscellaneous" bestseller list.

[5][14] Some of McDougall's dietary recommendations are in line with mainstream nutritional advice, such as an emphasis on fruits, vegetables and whole grains, but others are considered extreme and are not supported by evidence.

[19] Reviewing The McDougall Program: 12 Days to Dynamic Health, doctor Harriet Hall wrote that the book is filled with anecdotes and questionable statements, and that it makes many claims which are not supported by science.

[14] Hall concluded that "Some of McDougall’s recommendations are in line with mainstream advice, but there is reason to fear that strict adherence to his whole Program might result in nutritional deficits that could do more harm than good.

[3] McDougall wrote several books, with his wife Mary contributing recipes, which had sold more than 1.5 million copies as of 2008.