The Mekeo tribe of New Guinea say that hunger for plant-foods comes from the abdomen, while hunger for meat starts in the throat. Many hunter-gatherers across the planet have a special word for being hungry for animal flesh. The Mbuti of central Africa call it ekbelu, the bantu-speaking tribes talk of dyikioilu, and Sanumá Indians of Northern Brazil, of nagi` -- a hunger that no amounts of cassava bread and bananas may satisfy.
Does that mean your craving for a steak or for a rasher of crisply fried bacon is a real physiological need? Not exactly. As of today, scientists haven't found any compounds unique to meat that our bodies just can't do without (and not for want of trying -- the meat industry would be happy to see such results). Most likely, the hunger that the hunter-gatherers are talking about is all about protein.
There is one thing that many animals such as cockroaches, minks, cats and humans, have in common -- and that thing is an innate craving for protein. According to the protein leverage hypothesis, proposed by Stephen Simpson and David Raubenheimer from University of Sydney, Australia, animals strive to meet a fixed protein target. Basically, if the amount of calories from protein in the diet falls below about 15 percent, we start to crave protein-dense foods.
There is one thing that many animals ... have in common -- and that thing is an innate craving for protein.
If you feed rats a very low protein diet (with only 2 percent of protein in it), they will start overeating as they try to satisfy their need for the nutrient. Similar thing happens with humans. In early 2000s, Simpson and Raubenheimer have done an experiment: They closed off ten volunteers for six days in a chalet in the Swiss Alps, were they could choose their breakfasts, lunch, afternoon snack and dinner from a buffet (admittedly, not a bad deal). But the foods some of the volunteers could eat were all low in protein but high in fat and carbohydrates, while a second group was fed a high-protein diet (low in fat and carbohydrates). The results were clear: people on a low-protein diet kept overeating as they tried to satisfy their need for protein.
Later, other studies followed, involving larger groups of people, yet the results remained similar: give humans foods with little protein in them, and we start eating more and more in an attempt to satisfy our protein cravings.
All we need, though, is if about 15 percent of calories in the diet come from protein. When Margriet Westerterp-Plantenga of Maastricht University, the Netherlands, compared the proportion of protein in the diet of people living in the in 50s and 60s in seven different countries, as diverse as Nigeria, Czechoslovakia and the United States, she discovered that it always hovered somewhere around that 15 percent.
Yet craving protein doesn't have to mean craving meat. It could mean craving peanut butter sandwiches. Although meat is a good source of the nutrient, so is peanut butter on bread, buckwheat, tofu and potatoes, which are as complete in protein as is beef or pork.
Admittedly, protein in many plant foods is not completely balanced in essential amino acids, but as long as your diet is reasonably varied, your body is perfectly capable of getting all the amino acids it needs -- it combines them itself, just as it gets different vitamins from different sources (vitamin C from your morning OJ, vitamin A from the carrots you ate at dinner). Some plants, though, are particularly low in protein -- and here lies the key to the meat hunger puzzle. In some parts of Africa, for example, everyday diets contain a lot of foods such as cassava and plantains, which are protein-poor. And if you eat nothing but cassava, your protein cravings will kick in. An adult man weighing 165 pounds would need to chew through about ten pounds of the plant a day to get the required protein -- versus about a meager 7 oz of chicken. No wonder he may get pangs of ekbelu, the meat hunger.
Does that mean we in the West need meat for our protein? Not at all. According to the American Heart Association, "most Americans consume more protein than their bodies need." That's bad news. Studies show that excess protein is detrimental for kidneys, and that too much animal protein may even increase your risk of cancer.
Peanut butter sandwiches are plenty enough.