Americans crave efficiency. We esteem cars that burn less gas for each mile driven, jobs that generate the most money per hour and mobile phones that pack the most capabilities into the smallest possible package. In short, we want bang for our buck.

But we skimp on efficiency when it comes to eating, because we just can't resist meat. According to the United Nations' Food and Agriculture Organization, Americans consume 275 pounds of animal flesh every year, more per capita than nearly any other populace on earth. (Floss, anyone?) This is an expensive habit in carbon terms. A 2007 study by the National Institute of Livestock and Grassland Science in Japan reported that producing one pound of beef produces the same amount of CO2 as does driving a small car 70 miles.

Also, the waste of land is staggering. According to a U.N. report titled Livestock in a Changing Landscape, almost one-third of the earth's ice-free land surface is devoted to livestock production, while only 8 percent is devoted to production of food consumed directly by humans (i.e., plants). As the earth's human population escalates, with a population of 10 billion expected by the year 2050, the stresses on our planet's resources will follow, especially if we continue to bring home the bacon and butcher the beef.

So what if we just cut big mooing, grunting mammals from the equation and looked to another source of protein? Something lower on the food chain, perhaps—like insects?

We wouldn't be the first large mammals to consume them. The brown bear will sink its teeth into elk and salmon when it can, but it also eats large quantities of moths, termites and ants, and for a creature so high on the food chain to stoop to the bottom for its sustenance is a model act of humility that humans might do well to emulate.

Insects and other arthropods, like most "lower" forms of life, abound, constituting an edible resource of tremendous biomass. Ants alone reportedly approximate about one-third of all terrestrial animal biomass, according to ecologists' models. Add termites, moths, spiders and cockroaches to the menu, and we suddenly have a bounteous resource scuttling about innumerably at our feet, in the cracks and crevices and vile, damp places of the earth, a vast source of protein and minerals almost entirely untapped.

Eating bugs makes so much sense, in fact, that the U.N. is giving consideration to the matter. In February 2008, the Food and Agriculture Organization hosted a workshop called "Forest Insects as Food: Humans Bite Back" in Chiang Mai, Thailand. There, 36 entomologists, edible insect nutritionists, foresters and others with a stake in the developing edible-insect movement discussed the potential of six-legged animals as food and the challenges of developing a market and industry for them. The BBC reports that a handful of Dutch companies have already begun breeding beetles, crickets and locusts for food.

Even here in the United States, advocates are pushing the concept. The entomology department of Iowa State University posts online nutritional information about eating insects, while numerous cookbooks, including Creepy Crawly Cuisine: The Gourmet Guide to Edible Insects by Julieta Ramos-Elorduy, tout the wisdom and sense in eating earth's most abundant terrestrial animal resource and offer recipes like fried grasshoppers, ant larva tacos and mealworm cookies. Eminent entomologists like Gene R. DeFoliart, a bug-eating advocate at the University of Wisconsin well known to many in the insectivorous community, also vouch for insects as food. And some high-end restaurants, such as Mezcal in San Jose and the increasingly famous Typhoon at the Santa Monica Airport, are putting insects on their menus.

You might say the insectivore movement is gaining legs. And they're wiggling.

Bottoms Up

Just why creatures can be categorically defined as sustainable or not-so-sustainable food sources can be understood with a quick look at the trophic energy scale, a conceptual representation of organisms and the energy each one requires to grow and reproduce. At the apex of the pyramid scale are the meat-eating predators, like tigers and bluefin tuna. At the bottom are the simplest organic building blocks of life, like algae and phytoplankton, which often require little more than sunlight to grow. In terms of biomass, there is very little of the former and vast quantities of the latter.

The critters at the bottom of the trophic pyramid are better choices for food, not only because they're plentiful. They're also efficient. It is through algae and phytoplankton that the energy of the sun is first absorbed into the food web through photosynthesis. As energy ascends the pyramid, however—from phytoplankton to krill to sardines to tuna, from bacteria to grasses to grazers to carnivores—energy efficiency is lost rapidly. For every pound of flesh at the top of the trophic pyramid, immeasurable quantities of energy have been expended to make it.

Casson Trenor, the senior markets campaigner with Greenpeace and a former consultant with the sustainable-seafood nonprofit Fishwise, explains basic trophic math using two of the creatures he knows best, tuna and sardines.

"To take our protein from the level of tuna is a totally inefficient use of the ocean," says Trenor, who in 2007 founded the sustainable sushi restaurant Tataki in San Francisco and who recently received Save Our Shores' Ocean Protection Hero of the Year award. "If we want a pound of protein, we could get it from sardines. If we need to get it from tuna, it might have taken 15 pounds of protein from sardines to make that pound of tuna protein."

Thus, the lower we eat on the food chain, the more sustainable our diets become. The invertebrate level is a good place to settle down and make a meal, for these spineless species are excellent processors of energy. On average, invertebrate species utilize 20 percent of assimilated energy (i.e., food ingested and not pooped out) for growth and reproduction. Vertebrates, by contrast, use just 2 percent of assimilated energy for growth and reproduction, the balance being used for nothing but fueling motion and metabolism.

Of course, a vegetarian diet is the most sustainable long-term nutrition plan of all. Plants not only draw their energy directly from the sun via photosynthesis, they do it efficiently, directing up to 85 percent of assimilated energy toward making more of themselves. Algae can double their biomass in hours just by soaking up the sun.

But the food business is show business, and no chef attains rock-star status by boiling primordial broths of microscopic nourishment. They gain fame by carving up beasts and grilling them. A restaurant in New Jersey called Café Arugula has even served up retired circus cats (read: "roasted leg of lion") at expensive special event dinners.

All the Little Fishes

At the EcoFarm Conference in Asilomar last January, where restaurateurs and food producers convened to discuss sustainable-food production, sardines were a hot topic of discussion. That sardines have become an esteemed item in the culinary world gives Trenor at Greenpeace reason to hope.

"Sardines are a powerful indicator of change in the seafood industry," Trenor says. "Sardines have been out of favor for a long time. They've been the poor man's food, processed down by the train tracks and eaten out of a tin."

At Fishwise, Bill Wall, business partnership program manager, says the economic downturn combined with an increased awareness of ecological dynamics has spurred interest in small fishes and other mollusks. Squid, for example, are a great choice for diners hunting low on the trophic scale.

"Unless you eat anchovies and sardines," says Lou Zeidberg, a researcher in Monterey working for UCLA, you aren't going to get any closer to phytoplankton than with squid." Sardines and anchovies both filter phytoplankton from the water. Squid—voracious predators, even the four-inchers—do not eat phytoplankton, Zeidberg says, but they eat the copepods and the baby fish that do. Moreover, squid grow marvelously fast, a key point in true sustainability. The familiar market squid—the sort usually dredged in flour and fried—rarely lives more than eight months, according to Zeidberg. Its rapid life cycle helps make the population resilient.

Wall at Fishwise says retailers that don't regularly stock smaller fishes and mollusks may just need to be encouraged. "The best way to see the items in the case is to ask your fishmonger," Wall says. "Let them know there is a demand for lower trophic-level items."

He adds that there are health, and not just ecological, benefits to eating species closer to the trophic base. "Seafood lower in the food web is typically lower in mercury and contaminants, too," he says. "Mercury and PCBs bioaccumulate, meaning they are found in greater concentrations higher in the food web. As a shark eats many small fish with low mercury levels, all of the mercury consumed by the shark remains in the tissue, making the mercury content of the shark many times more than the fish it eats." The same rule applies to tuna, known for its potentially dangerous densities of mercury.

Jiminy Bar Snacks

Those uninterested in seafood but wanting more than veggies might aim in between, at the meek of the earth. But insects need not be rendered into mere bar food, and cooking them at home can produce creative and tasty dishes, both savory and sweet. Iowa State University's entomology department recommends a "rootworm beetle dip," no small portion of which is beetles—a full cup of them, dried and roasted. Their site also includes recipes for "banana worm bread," chocolate chip cookies with dried crickets crumbled into the dough and "mealworm fried rice," calling for equal parts rice and larvae.

According to the same website, 100 grams, or about a cup, of grasshopper contains 20.6 grams of protein, 6.1 of fat and 3.9 of carbohydrates. (A three-ounce portion of lean beef, just under a quarter-pound, contains 27.4 grams of protein.) Caterpillar contains 28.2 grams of protein per 100 grams. The same volume of dung beetle contains 17.2 grams. And crickets are high in calcium.

Many gardeners know that dandelions and other weeds go well in salads. Fewer know that the common garden snail, Cantareus asperses (formerly known as Helix aspersa), does well when sautéed in butter and garlic (what doesn't?) and served in the shell in which it lived its life. Yep, the garden snail that ravages your chard and kale is among the snails esteemed as escargot. In fact, it was introduced to California from France, no less, in the 1850s as a food source, according to a UC Davis online report. It now lives around the world.

Although snails can reportedly carry diseases dangerous to people, Cantareus aspersus is ranked as a food item by those who know. The French harvest the snails in the fall and may set them loose in an empty fish tank for several days where they are allowed to feed on rolled oats for a clean change of diet. A subsequent forced fast of several days renders them ready to prep, cook and eat. Snails are high in protein, vitamins E and B1, magnesium, phosphorus and potassium and are low in fat—prior to the butter. Be forewarned, though: snails may carry a parasitic roundworm. If cooking fails to kill this parasite, it may kill you. Do your homework.

Staring at the Sun

Those who eat shark, tuna, beef and lion are—how do we put this gently?—pigging out on the world's precious resources. But what if we could draw our energy directly from the sun? Some believers say we can. They call themselves sungazers and claim that life can be lived without food as we know it. By staring at the sun while standing barefoot on barren sand, rock, mud or soil, the philosophy goes, one can photosynthesize sunlight into calories.

Mason Howe Dwinell, a former San Francisco resident, sungazed on and off for a year in 2003 and 2004, was featured in a documentary film and eventually wrote a book about his experience and philosophy. Though he never went more than three weeks without food, he does declare on his website (www.sungazing.com), "Yes, you can live without food." Dwinell, now of Vermont, suffered only minor damage to his maculae during his days of staring at the sun, but he says his vision never deteriorated.

Elsewhere, sungazing gurus have reportedly lived for years without food. The science behind the practice is not fully understood or thoroughly documented, but its advocates assure: With patience and faith, we can actually eat the sun.

I'd rather eat termites.

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