This 2009 book by Lierre Keith is a fascinating reflection on how ideology permeates people's eating habits. Ideology, then, is based on memes and that's a new and developing field of science.
John Michael Greer (the Archdruid) tells the whole story of the great cycle of the macrobiotic and vegan diets. The macrobiotic movement started in the 1970 and peaked sometimes in the 1980-1990s. Greer himself tried to follow the rules of the macrobiotic diet and he reports an experience similar to that told by Lierre Keith in her book "The Vegetarian Myth" with a Vegan diet. Both Greer and Keith suffered serious health problems with these diets until they finally decided to abandon them - and then felt much better!
The question of diets can be utilized to illustrate how memes propagate in the global mindsphere. Data from "Google Ngrams" provide the number of times that a word is used in books. It can be used to quantify Greer's claim that Veganism somehow supplanted Macrobioticism in a memetic cycle that covered a few decades. It is true: here are the data:
You can see how the "macrobiotic" meme went through a classic memetic trajectory, virally infecting the consciousness space of a fraction of humankind. Then, it lost potency and started fading. These data are up to 2008, if you use Google Trends to measure how many times the term "macrobiotic" was searched for in the Web, you see that it is in terminal decline from 2004.
If "macrobiotic" is a dying meme, that's not true for "vegan" which is still showing growth in both Google Ngrams and Google Trends, the latter showing the number of times that a term is searched for in the Web. Here are the Google Trends data:
So, veganism is still alive and kicking, but it is hard to say for how long. Most likely, it will follow the same cycle of the macrobiotic meme, peaking and declining in the coming decades. This is not so much related to whether one diet is better than another, or whether either or both diets bring benefits to the people following them. It is the hard law of memes - they have a life of their own and a limited existence time (*).
Still, the fact that there is so much interest in diets tells us something. What we eat is not just a question of survival - even though in Italy we have a saying that goes as "what doesn't kill you, fattens you." (**). Rather, what we eat is a cultural, political, and religious statement. Not for nothing, most of the world's religions tell to their followers that God worries about the details of what His sons and daughters eat or do not eat.
Today, many people perceive that the world's food industry is operating on the basis of a new kind of religion: the religion of growth. Granted, the growth of food production has been successful in eliminating the major famines that plagued the world up to a few decades ago. But the food industry's approach to feeding the world is, literally, a "scorched earth" strategy. It destroys the soil, kills everything, razes forests, destroys the fisheries, fills the planet with chemicals and more. In the West, the result is the obesity epidemics and plenty of health problem.
So, following a diet such as the Vegan one is mainly a political - perhaps religious - statement. A statement that many people feel like they need to make in order to fight the way they are treated by the food powers that be. We'll see more of this in the future and it wouldn't be surprising if a new diet-based religion will arise one day.
In the end, food and diets illustrate how difficult it is for humans to understand (let alone manage) complex systems. The human metabolic system is hugely complex and it becomes coupled to the chemistry and the biological activity of food, just as it is interlaced with political and economic questions about the opportunity of using more and more precious resources in order to produce certain kinds of food. The result is a giant confusion of different opinions that may veer all the way to physical attacking people who don't share the same way of thinking about diets. It happened during the 1st century AD and in more recent times it happened to Lierre Keith, attacked by vegan fanatics.
Memetics doesn' tell us how to manage complex systems, but it allows us to have some idea of how memes diffuse and fight each other in the human memesphere. So far, we can at least say that dieting memes grow and die as virtual viral entities, apparently independently of whether they are beneficial to people or not. Maybe one day we'll learn how to do better.
(*) We (myself, Ilaria Perissi, and Sara Falsini) have a paper that provides a theoretical assessment of these cycles. It is accepted for publication on "Kybernetes". If you like to have a preprint, write to me or to Ilaria at ilariaperissi(thingeything)gmail.com or Sara Falsini (sara.falsini(thingery)unifi.it)
(**) Quello che non ammazza, ingrassa
