March 15, 2016
When we eat, much more than food goes into our mouth–culture, religion, ethics, politics, social class, tradition, family history–they all go in too. All this other stuff is quite worrying for many people. As long-time food critic John Lanchester writes:
“Food makes us anxious. The infinite range of choices and possible self-expressions means that there are so many ways to go wrong. You can make people ill, and you can make yourself look absurd. People feel judged by their food choices…”
So how did we arrive at this state where food can provoke anxiety rather than pleasure? Why, for so many people, has food become more than “just food”? That is a vast topic over which much ink has been spilled, and lies far beyond the scope of a short Internet essay. But, there are some worthwhile hints and many useful lines of inquiry to pursue. There is lots of “food for thought”!
Food and Nutrients
We live in the world of other animals and plants that, like us, are busy ingesting nutrients — the things that our bodies require in order to function. Nutrients are divided into two groups:
- macronutrients (sugars, carbohydrates, protein and fats)
- micronutrients (vitamins and minerals).
Food on the other hand, is what people in any particular cultural group classify as something they can eat or should eat, chosen from the array of nutrients around them. And cultures differ a great deal around this simple classification where what are considered to be foods are carved off from what are merely nutrients.
Much of the world’s population, for example, eats insects and insect larvae. In the “west” if we find these in our food we would probably conclude that it was contaminated. We are disgusted, and likely to throw out anything the “bugs” were in contact with (a box of cereal perhaps).
Yet, many of us in the West eat eggs. In a great many cultures eggs are thought to be disgusting bits of encapsulated mucus excreted from birds and reptiles. Ick!!
Sometimes potential foods have religious connotations too—things you should eat only on certain days, or should never eat at all. The list of these differences could fill volumes. And, over the eons of our own past, humans (and even our most distant pre-human ancestors) have eaten many different things, but especially eggs and insects. These foods after all, are pretty easy to get. If our ancestors had not eaten these foods, we probably wouldn’t be here.
Animals that rely on just one thing are liable to become extinct when the environment stops producing what they require. They are superbly while living in stable environments but don’t weather changes to their diet very well. We humans on the other hand, have been surfing on environmental diversity and change for most of our evolutionary history. It’s worth asking what that could mean if humans create a much simpler environment in the future: one characterized by the extinction of many other forms of life. For most creatures (including humans) that rely on environmental complexity, that could also be a pretty certain dead end.
Humans are omnivores: we can consume many different kinds of life forms in order to perpetuate our own lives, for such is nature. Or as humorist Woody Allen once said, “Nature is…big fish eating little fish, and plants eating plants, and animals eating…It’s like an enormous restaurant…” 
Fortunately, we can eat almost anything from the menu of life’s big restaurant and use it to survive. But that is also what writer Michael Pollan refers to as “The Omnivore’s Dilemma”. What would be best to choose? Since people feel very strongly about what they (and others) order from the menu, there is a great deal of room for uninformed opinion to masquerade as some kind of “fact” about food.
What to Eat
After reviewing many kinds of diets and their recommendations we basically agree with Michael Pollan’s admonition in his book In Defense of Food: An Eater’s Manifesto:
“Eat food. Not too much. Mostly plants.”
That is probably the wisest course of action over the long term for most people, most of the time, if they want to be as healthy as possible, but that still leaves lots of room to maneuver; which plants? And which animals? What is “not too much”? And when should we eat them?
Stephen Le, in his insightful book 100 Million Years of Food refines this message somewhat by concluding that for most people a predominantly plant-based diet is best consumed when one is younger–reserving more of the animal-based foods for older age. He emphasizes that walking and eating traditional foods of one’s own culture are also helpful. Le’s message: “Eat good food, keep moving, and let your body take care of the rest” is certainly wise. But what constitutes good food and how your body deals with that if it is already been compromised in various ways is not always easy.
People who wish to lose weight over shorter periods of time usually go on specific diets to help them accomplish that. Most of these usually work, at least for a while, for the simple reason that they restrict calories. And, after people stop their diet, they usually gain back the weight they lost, and far too often a bit more than they started with. That’s a real problem. Along with meaning that most diets just don’t work, serious health issues can develop when people rebound from diets and gain even more weight over the longer term. Where there are clinical studies that evaluate both the short and long term results of specific diets, we refer to them in the sections where we describe specific diets in more detail.
Most short-term diets result in temporary weight loss, mainly because they restrict foods from the calorie laden quick energy sources associated with sugars and carbohydrates that are so prevalent in contemporary Western diets. Some of those same benefits can also be obtained from short periods of fasting. Over longer periods the intake of a variety of foods is more likely to provide important micronutrients, and frankly, that’s just more interesting and pleasurable. And it’s easier to do. Shorter fasting periods are less likely to have ‘rebound’ effect.
To work over the long term, diets have to change what kinds of foods people eat, not just the amounts they eat. People also have to change their lifestyle to include more physical activity, which is difficult to do if a person on a diet has little energy. To keep weight off, change has to be transformational, not temporary.
Humans are omnivorous because of the many challenging environments in which our species has lived. Our bodies’ structures also reflect the many environments in which human beings have evolved over millions of years. Our ability to survive an inconsistent supply of foods–the equivalent of periodic fasting–also developed over long periods of time. This flexibility is an amazing asset, but it can become a liability too, particularly when people become obsessed with small parts of it at the expense of a varied diet. Our history is wrapped up with foods that we value, trade for, fight over and continue to fret over. It’s an amazing story, and so we will also provide a few references to good reading along the way. But to get us going, let’s start with some basic information, and a bit of “food for thought”.
Humans have relatively small digestive systems for an animal their size. We can also digest plant or animal material simultaneously. So, we can eat a ham sandwich–a difficult or even impossible task for many animals.
Classic predators usually have very large and highly acidic stomachs capable of handling large amounts of food at one time, and small intestines which are mainly for eliminating waste material.
Animals that eat almost exclusively vegetable material usually begin their digestion of carbohydrates with digestive enzymes found in their mouths. This is something humans can do along with most plant eaters. Neither do we have especially acidic stomachs (and if we do, it usually means we are uncomfortable and prone to develop an ulcer). Plant eaters have relatively smaller stomachs but very large chambers (usually large intestines) for breaking down fibre and releasing usable nutrients. For example, one of our nearest relatives, the Gorilla, consumes huge amounts of leafy plant material over the course of a day, and their large abdomens reflect that. Basically humans are a mixed bag of abilities–we can do it all, but there are tradeoffs because we can.
Another aspect of human anatomy that is related to our evolutionary history is our large brain relative to our body size. A big complex brain which is mostly fatty tissue requires a lot of energy to keep it humming along. It also requires sleep, basically to re-boot itself for the next day and to conserve a bit of that energy requirement.
Animals have to live within an energy budget in order to survive. Having one organ that requires a great deal of energy means that some other aspect of the animal’s anatomy will likely be reduced. For our size, along with a smaller than expected digestive tract, humans are relatively weakly muscled.The average Chimpanzee for example, is far stronger than any human being can ever hope to be. So, possessing a large brain sitting atop a relatively weak body with a smallish digestive tract required a relatively steady stream of high density nutrients in order to evolve. We require them today in order to be maintained. Being omnivorous definitely helps with this–it makes much more of the nutrient environment available as food. It also means that we can choose a healthy diet by eating a variety of both animal and vegetable based foods, or by carefully focussing mostly one kind or another.
Humans also have rather weak jaws and small teeth compared to other animals our size, including our closest relatives and our own ancestors. Ever since humans tamed fire and started to cook food, our jaws have been steadily declining. Cooking basically softens and pre-digests food to a certain degree, making it easier for our smaller digestive tracts. This makes most nutrients more accessible. It doesn’t mean we can’t (or shouldn’t) eat at least some raw foods. But we don’t have to, and judging from the cultural history of food traditions from around the world, mostly we don’t.
One other thing which is essentially human and is related to acquiring food, is living in highly social groups. One person may not be able to hunt, harvest or scavenge very successfully, but a cooperative group can be formidable. The sometimes exhausting task of processing food before eating it is also far better handled by a work party than by one person. Many hands make light work, as the old saying goes. Cooperation defines us most as a species–nothing we have achieved could be done alone.
We should not forget that eating is a highly social activity; that is one of its greatest pleasures. This very website is a good example of that valuable sociability too. It is a cooperative endeavour meant to maximize our collective well-being.