I have a book on traditional Hindu meditation, and in the chapter on diet the author admits that a high degree of vegetarianism may not determine how successful a country is... the Western countries are notoriously high in the amount of meat we consume- and how hard it is to get away from a meat-heavy diet. (McDonald's anyone?)
I wonder...
The countries that are successful today are mostly just those which had an opportunity to develop industry very early, that is, those in close communication with Britain- Western Europe, Russia (thank you Peter the Great), and America- which mostly all happen to have a high supply of coal, not just for burning but as an ingredient in making steel, providing the carbon.
In other world, the leading countries have simply had a head start in developing industry and also had the coal for it.
In the preindustrial world the leading countries were virtually always in India, China and the Middle East.
Sassanid Persia, Parthian Persia, the original Islamic Empire, the Mauryan Empire of India, the Gupta Empire of India, the Kushan Empire of India, Han China, T'ang China, Song China, Ming China, Qing China in the 18th Century, the Chola Empire of India, the Rastrakuta Empire of India, the Mughal Empire, Safavid Persia, the Ottoman Empire, Mamluke Egypt. Just to mention some of the more prominent ones. Look them up- or read about them in my own histories, starting with 'Song of The Age of Wonder'!
Look up Chinese art and music, Islamic art and music, Indian art and music, the Islamic Golden Age, Indian architecture, Islamic architecture, Chinese porcelain, Chinese inventions, the Ramayana, the Mahabharata, Journey to the West (in this case the West is India!), Romance of the Three Kingdoms, the Shah Nameh of Firdausi, Rumi, and the teachings of sages like The Buddha, Confucius, Muhammed, Mahavira, Jesus, and Lao Tzu for some of their achievements.
India, China and the Middle East are all highly vegetarian.
(Chinese fast food in America has lots of meat. But Chinese fast food was invented in America- it is definitely not typical of China!)
India is the country that was promoting vegetarianism in the book I was reading. Indian food is mainly plant and dairy based.
Middle Eastern food is mainly plant and dairy based. Despite depictions of fishing in tomb paintings, the ancient Egyptians too ate very little meat or fish.
And China is the country that invented Tofu. Some parts of China rely partly on fish, but most of China is a great breadbasket, with lots of grain- especially the parts that make up the heart of the Chinese Empire of old, and include the two biggest cities today.
As we have seen, the Chinese developed tofu- indeed, the ancient Chinese developed many fine forms of false meats based on soy, including probably the things that fake soy meat is based on today in vegetarian circles.
Not only were China, India and the Middle East the dominant countries in the preindustrial era, but their ages of great power were far more peacepul and stable compared with European history from the Rennaissance on- with the Habsburg wars (such as the Thirty years War), Napoleon's wars, and then the two World Wars and the Cold War.
The great successful eras of India, China, and the Middle East were much more stable and peaceful. The early Islamic era, for example, had nothing like Napoleon's wars.
Now, why should a vegetarian diet make a country more successful?
Simple.
Meat causes stomach aches. Meat is hard to digest.
(No, sadly, a clean conscience does not make a country more successful!)
And it would make such a big difference if a country supported vegetarianism in its restaurants and stores- America certainly doesn't! Try to find a low-cost vegetarian restaurant in America! (or any restaurant with lots of low-cost vegetarian food!) Try and find Tofu or Tofu Dogs in a typical grocery store! (and for a low price!)
And just look: it works.
What countries are rising as great powers despite very much not getting a head start in the Industrial Revolution?
India and China.
And India despite having relatively little coal. India relies on the microchip, and had to wait until the computer era, when the economy was no longer based so much on making vast amounts of steel from iron and coal.
India, China, Egypt and Persia: the great Vegetarian Empires of the preindustrial world.