Among the many diet books published each year, there are a few nutrition books that step back and offer an explanation of the tangled web between Americans and their eating habits.

The latest book to attempt this is “Food Matters: A Guide to Conscious Eating” (Simon & Schuster, 2009) by Mark Bittman, a long time food columnist for the New York Times. What makes Bittman’s advice more compelling are his statistics, energy ratios and comparisons with the developing world.

The trigger for writing “Food Matters” was the 2007 United Nation’s Report, “Livestock’s Long Shadow,” where it is shown that livestock creates more global greenhouse gases than transportation.

Here are some telling ratios: While 1 kilocalorie of corn takes 2.2 kilocalories of energy to produce, 1 kilocalorie of beef requires 40 kilocalories of energy. (1 kilocalorie = 1 diet calorie.)

To raise a steer takes the energy equivalent of 135 gallons of gasoline. So a typical family (of four) consuming a steak dinner involves the same amount of energy (in the meat) as driving a SUV for three hours.

The problem with high meat consumption is that it involves so much crops (tying up land, much fertilizer and water) devoted to feed the animals, who are often raised in crowded stalls, fed low level antibiotics and often growth hormones.

Seventy per cent of the world’s cropland is devoted to raising crops for the animals and for ranges for them to move about. Currently, 60 billion animals (cattle, chicken, pigs, turkeys) are eaten by humans every year; this is about nine animals per global human.

In America, with a population of 303 million, each year we consume 9 billion chickens (30 chickens per American!), 250 million turkeys, 100 million pigs, and 36 million cattle.

In the year 2000, each American consumed an average of 195 pounds of meat, chicken and seafood, a little more than a half pound a day. To feed these animals, American farms used 50 percent of their corn and about one-third of their soybeans.

It’s troubling that livestock is the fastest growing component of global agriculture. Since 1980, the number of pigs and poultry have quadrupled and the number of cattle, sheep and goats have doubled.

The United Nations Food and Agriculture Organization predicts that the number of farm animals needed for human consumption will double by 2050. How will the world support the raising and feeding of these 120 billion animals destined to be human food each year?

American now eat three times the global average of meat and poultry; we have epidemics of obesity and diabetes with many Americans having some form of cardiovascular disease. America, among the major industrialized countries, now lags in life expectancy (yet we spend more per capita for health care than any other country).

Until large farms began the extensive use of fossil fuels for machinery, fertilizer and transport of food, it was a struggle for most people to get just an adequate number of calories.

Now, many Americans can eat as much meat as royalty could in the 1700s. Back in those times, meat for the common people was a luxury reserved for special occasions and savored, not eaten several times a day.

If less meat is consumed, it means that more crops can be raised for humans to eat. Then there will be more vegetables, fruits, legumes, nuts and healthy oils for us to consume. Chickens will go back to their primary role as egg layers and cows as milk producers.

Sky and show

At dawn today, a slender crescent moon was low in eastern dawn near the bright planet Jupiter.

Late Wednesday evening, the moon will swing from the morning to the evening side of the sun (New Moon). This Friday, the crescent moon will appear near the brilliant planet Venus low in the southwest at dusk.

Our last showings of “Tropical Skies” will be today at 4 p.m. and 7 p.m. at the Frostburg State Planetarium in Tawes 302. Following our 45-minute program, any interested will be invited to tour Frostburg State’s Science Discovery Center in nearby Compton Hall.

Reader’s questions or comments can be sent to rdoyle@frostburg.edu or left on a voice mail at (301) 687-7799.