For specific advice on a high quality lifetime diet, see the article on the Goddess diet plan.
A semi-vegetarian diet is one the mostly includes food from plants and excludes most foods from animals, but allows fish, seafood, insects (including honey), eggs, cheese, milk, and other dairy products (and often allows gelatin as well).
I have no doubt that it is a part of the destiny of the human race, in its gradual improvement, to leave off eating animals., Henry David Thoreau.
I do feel that spiritual progress does demand at some stage that we should cease to kill our fellow creatures for the satisfaction of our bodily wants., Mohandas Karamchand Ghandi.
Oh, my fellow men, do not defile your bodies with sinful foods. We have corn, we have apples bending down the branches with their weight, and grapes swelling on the vines. There are sweet-flavored herbs, and vegetables which can be cooked and softened over the fire, nor are you denied milk or thyme-scented honey. The earth affords a lavish supply of riches, of innocent foods, and offers you banquets that involve no bloodshed or slaughter; only beasts satisfy their hunger with flesh, and not even all of those, because horses, cattle, and sheep live on grass., Pythagoras (Greek mathematician). Pythagoras ate bread and honey for breakfast and raw vegetables for supper. He also paid fishermen to throw their catch back into the sea.
Can you really ask what reason Pythagoras had for abstinence from flesh? For my part I rather wonder both by what accident and in what state of mind the first man touched his mouth to gore and brought his lips to the flesh of a dead creature, set forth tables of dead, stale bodies, and ventured to call food and nourishment the parts that had a little before bellowed and cried, moved and lived. How could eyes endure the slaughter when throats were slit and hides flayed and limbs torn from limb? How could his nose endure the stench? How was it that the pollution did not turn away his taste, which made contact with sores of others and sucked juices and serums from mortal wounds? It is certainly not lions or wolves that we eat out of self-defense; on the contrary, we ignore these and slaughter harmless, tame creatures without stings or teeth to harm us. For the sake of a little flesh we deprive them of sun, of light, of the duration of life to which they are entitled by birth and being. If you declare that you are naturally designed for such a diet, then first kill for yourself what you wnt to eat. Do it, however, only through your own resources, unaided by cleaver or cudgel or any kind of ax., Plutarch (Roman historian).
It may indeed be doubted whether butchers meat is anywhere a necessary of life. Grain and other vegetables, with the help of milk, cheese, and butter, or oil, where butter is not to be had, afford the most plentiful, the most wholesome, the most nourishing, and the most invigorating diet. Decency nowhere requires that any man should eat butchers meat., Adam Smith (British economist).
Let the advocate of animal food force himself to a decisive experiment on its fitness, and as Plutarch recommends, tear a living lamb with his teeth and, plunging his head into its vitals, slake his thirst with the steaming blood then, and then only, would he be consistent., Percy Bysshe Shelley (poet).