The Fasting Cure is 1911 non-fiction book on fasting by Upton Sinclair. It is a reprinting of two articles written by Sinclair which were originally published in the Cosmopolitan magazine. It also includes comments and notes to the articles, as well as extracts of articles Sinclair published in the Physical Culture magazine. The book is dedicated to Bernarr Macfadden.

Sinclair was keenly interested in health and nutrition. He experimented with various diets, and with fasting. He writes extensively about fasting in The Fasting Cure, which became bestseller. Sinclair believed that periodic fasting was important for health, saying, "I had taken several fasts of ten or twelve days' duration, with the result of a complete making over of my health". Sinclair favored a raw food diet of predominantly vegetables and nuts. For long periods of time, he was a complete vegetarian, but he also experimented with eating meat. His attitude to these matters is fully explained in the book's final chapter, "The Use of Meat". The book makes sensational claims of fasting curing practically all diseases, including cancer, tuberculosis, asthma, syphilis, and the common cold. Sinclair has been described as "the most credulous of faddists" and the book is considered an example of quackery.

Upton Sinclair was an prolific American writer who won a Pulitzer Prize in 1943. Sinclair was obsessed with health and nutrition and often experimented with various diets, and with Fasting. In this book he talks about how fasting cured many ailments and had the added benefit of high fat loss. He wrote The Fasting Cure in 1911 and it went on to be a best selling book.