Meat production is environmentally problematic. The emissions are worse than your car. The ethical issues are worse than those in any Ed Norton film.
Oh, the resources. Meat is so packed with protein and fats that a stomachful is much more than you need. And there's the fact that making meat requires vast amounts of food and cleared land. Problems abound – but so does the demand for meat, despite it being patently clear that we need to eat less of it.
According to the New York Times, the world's total meat supply in 2007 was 284 million tons. Since Americans eat an average of 8 ounces of meat every day – or over 180 pounds a year – this means that if the entire population of the world switched to American meat-eating habits, it would require around 550 million tons a year. Put another way – we'd need two planet Earths to produce enough meat to feed everyone.
Asking the calorie needs of the average human being is a little like asking how long a piece of string is – but as a broad, shot-in-the-dark figure that neglects to account for fitness, exercise, metabolism and a host of other factors, the average human male needs around 2,500 calories and the average woman about 2,000. That's what we need to function. Any extra gets stored away by our bodies for a rainy day.
Americans are not efficient eaters. The calories consumed per day by the average American in 2008 was 3,750 (in a population of 303 million), according to the World Resources Institute. Compare this with the 2,500-calorie average in India (population – 1,147 million). Put thus, the food consumed by Americans could feed 39% of India's population – even though America contains a quarter of the people.
Right now, world hunger is a pressing issue. Some people aren't even getting the minimum they need to survive. In 2006, world salt production was an estimated 240 million tons. Of this, around 17% goes towards making edible salt. If the entire world switched to eating 12g of salt a day, that would be around 30 million tons of salt, or just 12.5% of total world production levels. There's the worry – it could happen. (The reason is that world salt production is higher than ever – in fact it appears to have tripled since 1960′s estimated 85 million tonnes).