In this book, Smith offers both lifestyle and dietary advice, from a vegan perspective. Smith explains that the shift to an animal-free vegan diet needs to be introduced gradually for invalids and those who are ill. However, she qualifies this statement with the observation that meat is not necessary to human health. She recommends removing meat along with tea and coffee, while reducing animal products and spices. Citing a "fruitarian" experiment in California (resonant of Isaac Rumford's community at Joyful), which she also terms the “Edenic” diet (35), Smith advises against the raw-food approach to veganism, describing instead: “bread and fruit, to which nuts may be added if desired. This method has been adopted by large numbers and seems to fulfill every requirement in the human economy” (35).

The complicated contemporary understanding of whether “vegetarianism” means excluding only meat or refusing all animal products is addressed in one of her introductory chapters, “Who are Vegetarians, and What is a Hygienic Diet?” She reports a conversation with a purported vegetarian who reveals that she eats fish. When challenged, this pescatarian asks, “is eating fish any worse than using animal products? And you know nearly all the vegetarians use those; indeed, feel that they could not get along well without them.” Smith's reply is framed as a “vegetarian” response yet it represents a proto-vegan criticism of  this highly restricted understanding of vegetarianism as a refusal only to consume flesh. Her critique is framed in ethical vegan terms:

Then let us announce ourselves just what we are — non-flesh eaters. We boast that no animal need be slain that we may be fed, that seeming to be the main point. But thousands of young are robbed of their natural food and slain that we may have milk. We do not kill the hen that we may have eggs, yet we rob her nest and eat the undeveloped chickens. The one, as you see, a 'milk machine,' the other an 'egg producing machine,' so it is no great sacrifice to give up flesh eating when we partake abundantly of these concentrated nutrients, fish included (38).

Smith suggests that animal products like milk and eggs are, in fact, meat under a different name. This explanation exposes her “vegetarian” interlocutor as being no vegetarian at all and she confesses, "I believe you are right, but I never had the subject presented to me in this way, and am sure I could not be a strict vegetarian" (38).

This reported dialog is prefaced by Smith's survey of the diverse dietary regimes that go by the name “vegetarian” and echoes the debates that led to the coinage of the term "vegan" some forty years later, in 1944. Smith rejects the definition of vegetarian as “One who eats no meat,” explaining that “[i]f by meat is meant flesh foods merely, then it were more consistent to call such people 'non-flesh eaters' instead of vegetarians, as the name is very misleading” (37). She then surveys the variations of “vegetarian”:

There are four classes of earth productions, — grains, vegetables, fruits, and nuts. There are two classes of people, the meat eaters and the non-meat eaters. Of this latter class there are several divisions. Those who live on nuts and fruits are called fruitarians. Large numbers live on bread and fruit, many of them including nuts; to these, others add vegetables, cereals, and vegetable oils, and these constitute the true vegetarians, living entirely upon the vegetable productions of the earth” (37).

The recipes that constitute the bulk of the book largely follow her prescription for “true vegetarians” while also offering advice for those who are on the gradual journey away from animal products towards a truly vegetarian diet.