This book is a reprint of two articles written by Mr. Sinclair for the Cosmopolitan Magazine on the general subject of fasting for health, together with the most interesting of the numerous newspaper comments that they brought forth, and the most significant letters written to him by private individuals asking his advice and detailing their own experiments along similar lines. There are also extracts from some of the author's articles in the Physical Culture Magazine, from articles replying to his, and from other replies in rebuttal.