Fat

Hanne Blank

• Publisher: Bloomsbury Academic
• Year: 2020
• ISBN:
  9781501333293
• Edition: 1
• Topic: Literature
• Subtopic: Literary Criticism Theory
• Index: Literature

Object Lessons is a series of short, beautifully designed books about the hidden lives of ordinary things. Public enemy. Crucial macronutrient. Health risk. Punchline. Moneymaker. Epidemic. Sexual fetish. Moral failing. Necessary bodily organ. Conveyor of flavor. Freak-show spectacle. Never mind the stereotype, fat is never sedentary: its definitions, identities, and meanings are manifold and in constant motion. Demonized in medicine and public policy, adored by chefs and nutritional faddists (and let's face it, most of us who eat), simultaneously desired and abhorred when it comes to sex, and continually courted by a multi-billion-dollar fitness and weight-loss industry, for so many people "fat" is ironically nothing more than an insult or a state of despair. In Hanne Blank's Fat we find fat as state, as possession, as metaphor, as symptom, as object of desire, intellectual and carnal. Here, "feeling fat" and literal fat merge, blurring the boundaries and infusing one another with richer, fattier meanings. Object Lessons is published in partnership with an essay series in The Atlantic.

1 Fact

Let us begin, then, by doing the thing we don’t get to do, taking a good long look at the stuff we only think we’re seeing when we see love handles or double chins or beer bellies. To consider fat this way is—as something literally more than skin deep and with a material existence of its own—a way of beginning to expand our thinking about fat. Human fat, like the fat of other mammals, is relatively solid at room temperature, a trait it owes to the long fatty acid molecules that make it up. Every fat molecule has a fatty acid attached to a glycerol molecule, and it is those fatty acids that make different kinds of fat so diverse. They affect the ways the molecules stack and how sturdily stacked the molecules are. Some will melt in the mouth or on the skin like the cocoa butter in chocolate, others require significant amounts of heat before the stacks of molecules slowly disintegrate into liquid. Lard, for example, is made through precisely that process: the white, layered fat that forms around the kidneys of pigs is cooked in order to render the pure fat out of the organic tissue. Heat turns the fat liquid, and the liquid can then be poured off and prepared for use. Allowed to sit in a dish at room temperature—which has been standardized at about 20° Celsius or 68° Fahrenheit—lard will solidify. Fats that go solid at room temperature are called “saturated” fats. Unsaturated fat molecules remain liquid. There are other classes of fats as well, like semi-saturated fats, hydrogenated fats, and trans fats, some of which occur spontaneously and others that are generated through manipulation of fat molecules, but they are less important for our purposes. We’re here to talk about human fat, for the most part, and human fat is a saturated fat much like lard, solid at room temperature.

Like lard, much of human fat is white, or at least what is called “white fat.” Often in humans it is not white but yellow, stained by the vivid beta carotenes we consume regularly via foods like carrots, red peppers, and winter squash. Fat exists in many colors, both inside the human body and outside it. We’re familiar with the creamy hue of tallow, the greens and yellows of olive oil, the yellowy tan of beeswax, the red of palm oil. In humans, we add white (yellow), brown, and beige. Even at the level of color, the fat in our bodies is not all just one thing, one blob indistinguishable from the next. Not only do we contain multitudes, but so does our fat: white, brown, and beige fat each have distinctive identities and functions.

All forms of fat are part of the body’s survival team. White fat’s big job is to store energy in an easily available form. As a child, I recall being terrifically confused by this news: my mother’s chilly loathing of fat had taught me only that fat was ugly, unwholesome, and unnecessary. Then one day a pediatrician, having weighed me and pinched my chubby little kid sides with a terrifyingly large cold set of calipers, lectured me at length about how fat existed only to store extra energy so a person wouldn’t starve to death and, with a meaningful look over the tops of his eyeglasses, insisted I was clearly in no danger of starving to death. I knew perfectly well that squirrels got fatter before winter, having watched them feeding heavily under the oak trees in our Cleveland back yard, and I’d seen television documentaries in which bears fattened up for their long winter hibernation. Somehow I hadn’t put two and two together and realized that fat did the same thing in people. The available glycogen in fat cells is easily transformed by the liver into glucose, the body’s preferred fuel. Without glucose, cells literally stop functioning. Being deprived of glucose, for a cell, is just as bad as being deprived of oxygen. Take away a cell’s supply of either or both and it dies. That, at the cellular level, is what starvation looks like. Body fat helps maintain the glucose supply not only in times of actual famine, as the depth of winter so often is for squirrels and bears and other creatures, but during all the times when we are too ill to eat, too busy or stressed to make time for lunch, or too poor to have enough to eat.

Protecting us from starving is white fat’s primary job, but not its only one. It also releases hormones that help regulate metabolism, contributes to the protein-production process, insulates, and protects the skeleton and internal organs. A radiologist friend used to tell stories about her first internship weeks at a big Baltimore hospital, reviewing X-rays of people who’d been brought to the emergency ward with gunshot wounds. She often saw images without seeing the actual patients, and found herself sending out panicked reports about patients who had multiple bullets, broken-off tips of knife blades, and other startling and dangerous objects embedded in their bodies. The surgeons with whom my radiologist friend worked would laugh: they saw the actual patients, and knew from what they’d seen that they only had to worry about the bullets responsible for the raw, bloody, new entrance wounds they found. The rest could be safely left where they were, securely encased well beneath the skin, held by the patient’s body fat. Metabolically, and in some cases materially, fat can be an excellent bodyguard.

It is an interestingly bloodless place, this white fat, but don’t mistake bloodlessness for inertness. Most white fat is found under the skin, a subcutaneous layer of varying thickness. Although the skin itself is highly vascularized and contains myriad blood vessels and capillaries, veins and arteries, and the visceral body of muscles and organs is also chockablock with blood’s tubes and tunnels, the fat that lies between them is not. The same is true of visceral fat, white fat that has been deposited deeper inside the body. Fat is surrounded by vascular tissue but doesn’t often include it. White fat cells do not appear to require a lot of direct access to circulating blood. This is true despite the fact that fat cells are constantly productive, daily churning out supplies of substances that the body needs to function like estrogen, the inflammatory and insulin regulator called adiponectin, and a hormone called leptin that helps the body regulate its appetite for food. Lack of blood flow is no obstacle, nor does it keep fat cells from receiving all the chemical signals they need to do this job appropriately and in the right proportions. Even more impressive, white fat cells do all this without an internal energy source. Mitochondria, the subcellular organelles that generate chemical energy for almost all types of living cells, don’t exist in white fat cells. It’s one of the reasons they don’t have a distinctive color of their own.

Brown fat, the body’s other primary form of fat, does have mitochondria and is rich with blood vessels. Brown fat cells make their own energy and thus allow brown fat to contribute to our survival in a very different way, by generating heat. Babies have more of it, percentage wise, than anybody else for the simple reason that babies need the greatest amount of help regulating their own body temperature; we lose much of it as we grow to adulthood. As adults we have only a few ounces of the stuff, though women have a bit more than men and leaner people have a bit more than people with more white fat in their bodies. Whatever amount we may have, though, it is this brown fat that exists in the neck, between the shoulder blades, and in the spaces around the heart and kidneys, that lets our bodies keep the most vital vulnerable bits from getting cold. This thermogenic activity can only take place by using the energy contained in white fat. And this, of course, is of great interest to researchers who work on questions of how human beings might more intentionally regulate the amount of white fat in their bodies.

Sometimes, though not often, the body combines these two types of fat. “Beige Fat” has always sounded to me like a particularly good name for a punk band. In the body, it is exactly what it sounds like: a mix of white and brown fats that appears beige. Like brown fat, beige fat uses white fat cells to generate heat, and like white fat, beige fat stores glycogen for future use. We usually have even less of it than we do brown fat, located under the collarbone and along the spine. These few ounces of “specialty fats” are small but mighty, helping the body maintain the physical conditions it needs not only to survive but to thrive in this unpredictable world.

Beige fat tidily integrates all the aspects in which fat serves us as a survival mechanism. It seems competent in its multitasking way, efficient and helpful. But all fat does something useful, something the body needs, and something that only fat can do. This is why, when more food is taken in than the body can immediately use, it is stored against an unguessable, perhaps dangerous future. For every gram of fat metabolized—which is to say, converted back into usable glucose—the net gain in terms of energy from glucose is about 9 food calories, or to be a little more precise, 37 kilojoules. The availability of these grams of fat can be what makes the difference between life and death.

While we’re on the subject, a few words about calories: a calorie has no innate relationship to fat. It is actually a measurement of heat energy, first introduced by the French physicist Nicolas Clément in 1824. A calorie, rather unglamorously, is merely the quantity of heat energy needed to raise the temperature of a precise quantity of water by one degree Celsius. Calories come in two sizes, based on the size of the quantity of water in question. “Small” calories function at the level of grams—how much heat energy it takes to raise the temperature of one gram of water by one degree Celsius—while the “large” calorie, standardized for use by nutritionists by American chemist Wilbur Olin Atwater in 1887, functions at the level of the kilogram. Measuring calories is a way of answering the following question for any given substance: Assuming standard atmospheric pressure, how much hotter could we make a kilogram of water using only the potential energy present in this substance? An Oreo cookie, for instance, could raise the temperature of a kilogram of water by about 53 degrees Celsius. It wouldn’t be able to keep the water at that temperature, or make it any hotter. For that, you’d need more Oreos.

A calorie is not an object, not an item or a substance of which one eats either too many, too few, or possibly exactly the right amount. Search all you like, sift through every atom of your most recent meal, you won’t find its calories anywhere. Not in cottage cheese, not in croissants, not in chocolate. This is true even though in theory anything that can be burned—a stick of firewood, a stack of old love letters—could be measured in terms of its caloric output, which is to say the heat it can generate. “Calories” is just another way of talking about the potential energy bound up within the molecules of a substance. Calories aren’t things. The calorie is a concept, a unit of measure that allows us to quantify the potential energy bound up in the molecules of a substance.

Because the calorie is a unit of measure we could, if we liked, measure the energetic potential of a US gallon of gasoline (about 4 liters) is to say that it equates to about 31,000 calories. This is accurate, but it seems strange to think of it this way. This is because we have been taught since childhood not only to think of calories as things but as things that are specifically, and solely, found in food. Food “contains” calories, or so the nutrition labels that have been increasingly included in the packaging of prepared foods since 1973 (when the US Food and Drug Administration began to regulate them) have taught us to imagine, listing calories alongside other nutrients like protein, fiber, and vitamins. As a result we have come to think of calories as a representation of how “foody” a food is. “Low-calorie” foods are foods that, per unit of volume, do comparatively less of the central thing that food does: provide our bodies with energy. There are two ways to think about this. One is that low-calorie foods require us to eat a lot of them in order to obtain the energy we need, and therefore it’s more difficult to obtain any useful excess. The other is that low-calorie foods allow us to eat a lot of them without obtaining all the energy we might need, thus lowering the chances that we will obtain any unwanted excess.

Which brings us back to fat. Human beings are not controlled environments. We are made of more than water, and our metabolic processes do not much resemble the excitingly named bomb calorimeters with which Atwater and others measured the energetic potential of foods. The reactions are far more complicated, to say nothing of the fact that we need much more from what we eat than just energy that can be turned into body heat. Cold-blooded creatures don’t use their food energy to warm their bodies, after all, and as my anthropologist friend Keridwen Luis has been known to quip, “Even lizards have to eat.”

It’s been obvious for some time that in humans there is not a clear, one-to-one relationship between calories consumed and body weight. Yet in generating numbers to describe the energetic value of food, we have created the opportunity for a seductively simplistic belief about calories in versus calories out. It’s a bit like thinking of the body as a bank: the more you put in and don’t spend, the more you save (as fat) and the bigger your (fat) savings become. If you put in very little and spend a lot, your savings will dwindle. (Ironically for our late-capitalist culture, it’s the one time we are encouraged, even bullied, to leave nothing whatsoever in the bank.)

This is true in large outline, but as ever, the devil is in the details. Unlike mechanical engines which have a fairly constant rate of energy utilization, bodies may need either more or less energy depending on environmental circumstances or internal body conditions. Also unlike mechanical engines, bodies can adjust, within limits, to a lack of food energy. As University of Minnesota researcher Ancel Keys discovered in his landmark 1945 experiment (generally known as the Minnesota Semi-Starvation Experiment), human bodies literally slow down and shrink the physical system so that the organism can survive with less energy. Keys’s thirty-six volunteer subjects, many of them conscientious objectors who chose to participate in the starvation study rather than enlist in the Second World War, did not merely become alarmingly thin during the experiment’s starvation phase, whe n they were being fed 1,570 calories daily; they also lost about ten percent of their normal blood volume as their body temperatures sank, their hearts shrank in size, and their heartbeats slowed. The mechanical equivalent would roughly be like having a car that, after its gas tank or battery had emptied, did not sputter to a stop and refuse to start again until fuel was added, but rather shrank its engine and ran more slowly for an indefinite (although not infinite) period of time.

But this was not the only lesson Keys’s work, published in 1950 as The Biology of Human Starvation, had to teach us. Without sufficient energy in the form of food, human beings have trouble concentrating, lose interest in sex, and become depressed. Perhaps predictably, they also become preoccupied with food, a preoccupation that lasted long after the starvation phase of the experiment had ended, for Keys’s volunteers. Keys also observed a curious phenomenon that has, like all his results, been multiply corroborated since the 1950s: semi-starvation neurosis. The experiment’s subjects would spend hours nursing a single meal, even as their ability to concentrate on anything else evaporated. They became socially withdrawn, apathetic, and often neglected basic hygiene like brushing their teeth. The first time I read Keys’s work, in my twenties, I did so in search of some insight about how to lose weight. What I found was a very different kind of insight: a very clear demonstration and explanation of why, every time I went on a diet, I ended up feeling cognitively and emotionally like something that had been scraped off the bottom of a shoe.

As Keys’s study proved, human metabolism is both complex and dynamic, and importantly, the body’s basal metabolic rate, or the amount of energy the body needs when at rest, declines when there is a consistent lack of available food energy. The body actually adjusts what it needs as best it can to align itself with what comes in. This is a genius move, when it comes to survival. It is also a vexing move for people whose attempts to lose weight are stymied by the body’s ability to live on less. And this is not the only piece of the metabolic puzzle of fat. There is a considerable innate range of basal metabolic rates among humans. Our basic metabolic functions, such as keeping our bodies warm and oxygenated, building new cells, or removing waste products and other organic housekeeping, represent about 70 percent of our total energy use as humans. But how much energy, measured in calories, does that take? One study of 150 adults, performed by researchers at the University of Aberdeen, showed a range in basal metabolic rates from 1,027 calories per day all the way to 2,499 calories a day, a startlingly large variation. The researchers were able to account for about 75 percent of this discrepancy, which was largely attributable to body composition: lean body mass requires more energy to maintain than other types. Yet this still leaves us with what we might think of as 25-percent mystery. We simply don’t yet know all the reasons that one person’s body at rest might require literally one and a half times as much more energy than another’s.

This is not the only way in which fat is a mystery. On the whole, fat is a fairly law-abiding organ in our bodies, a reasonably predictable substance. The reason we rarely hear about diseases like liposarcoma, a form of soft tissue cancer that begins, as the name suggests, among fat cells, is that they are both relatively rare and, as their rarity suggests, are not something caused by fatness or more likely to occur in fatter people. We do not know why about two people in a million will experience the condition, only that it’s about twice as common in men and often occurs in areas of the body, like the neck, that we don’t actually tend to associate with fat. What is clear is that neither overall body fat percentage nor calories in versus calories out are part o...