National Cancer Institute, poster displaying high-fat foods, 1988

Calories! Has anything so frequently counted been so frequently misunderstood? As a unit of measure they share the ubiquity of units like ounces, grams, and pounds in our daily lives. However, their effects are altogether more ambiguous because of both their emotional baggage and the pseudo-scientific way in which they are calculated. Since their arrival on the scene 125 years ago they have actually changed the way we interact with food, something that would have seemed inconceivable considering how long we’ve been eating. Much like many diet fads before and after them, they are touted as a foolproof guide to health and weight loss; however, they set themselves apart from other fads by the extreme level of institutional success they have achieved in an era when food is more institutional than ever.

The calorie, as a unit, has murky origins; it first arose, in 1820s French physics and chemistry texts, as a unit of heat, namely, the amount required to raise the temperature of one kilogram of water one degree Celsius. Despite the fact that it was not formally adopted as a metric unit (and was eventually beaten out by the joule) the thermal calorie is the unit of heat used to calculate nutritional calories, the unit we now see listed on the back of every package. The word calorie entered the English language as a synonym for nutritional calorie with Wilfred Olin Atwater’s article in TheCentury Magazine, published in 1887, which outlined the equations used to calculate food energy as expressed in nutritional calories.

Calories as a unit of heat are measured by a bomb calorimeter, a device that incinerates food (or whatever item is being measured) completely in a small compartment surrounded by water, then measures how much that water goes up in temperature. At first glance, the connection to nutrition may seem quite puzzling; after all, however little we may know about the human digestive system, we can all be relatively sure that it’s not very much like incineration. Keenly aware of this problem, the aforementioned Atwater developed some equations to factor in the energy lost through elimination. Basically, the nutritional calorie, the number on the back of the label, is calculated by subtracting the energy of feces from the value attained by bomb calorimetry. In order to pin a value on the energy lost in feces, Atwater developed one digestibility coefficient for each macronutrient (carbohydrates, proteins, and fats), which approximates how much energy from each of these is lost through elimination. Though these calculations gave Atwater a reasonable approximation when compared to his experimental data (mostly gathered from babies and young men; who do you think would let someone burn all their poop?), several critiques are leveled at them; first of all, depending on one’s diet, age, gender, and individual constitution, might not digestion “go down” differently? And second of all, his system assumes the same exact digestibility across all types of each macro nutrient: beef, turkey, and lentils are all treated the same, but more problematically, so are starch, sugar, and fiber, the three types of carbohydrate. However, as anyone who has ever eaten a salad (fiber) and/or a piece of bread (starch) knows, these things are all digested quite differently; starches and sugars are actually digested almost completely, while fiber is hardly digested at all (this is why it’s considered so beneficial for cleaning out the colon). 

Despite these drawbacks, no one has really troubled to come up with a better system, so Atwater’s equations are still in use. Calories, however, are rarely calculated from scratch. Practically all calorie values on food products are just totted up using the government’s standardized lists of caloric values (calories for one beef patty plus calories for one bun equals calories for a hamburger, etc.), which have been available to the public in some form since Atwater published his own tables at the turn of the century. Of course, their accuracy is limited, as not all hamburger buns are created equal, or even of the same ingredients. As a result, some companies do independent measurements of their products if they think they’ll be audited by the FDA; McDonald’s sent in the side salad on their new Happy Meal, for example, to a private lab, as they no doubt expected to use the caloric data in advertising, and thus, get checked up on.

Rather more interesting than how calories are calculated is why. People had been eating food perfectly happily for millennia without being able to compare, say, apples and oranges. However, Atwater and others like him, nutritionists working in the field of public health, wanted to develop a way to compare different foods in terms of energy content (calories serving as sort of a giant common denominator through which any two items, however dissimilar, can be compared) and figure out how much rural laborers needed to eat a day to compensate for how much work they did; the US government in particular was interested in this one, as inadequate diets lower productivity and increase strain on the health care system. In their recommendations they placed an emphasis on calories per dollar, so foods like peanuts and beans were encouraged, though a diet of 100% peanuts or beans seems not only boring but, like all monodiets, nutritionally lacking. Calories expended were measured by determining respiration rate (how much carbon dioxide is expelled by a given person in a certain period of time), and from this value the government determined the caloric input necessary to avoid weight loss. This method was also used on livestock.

Soon, with the advent of World War I, the government had a new and compelling use for calories. Atwater, who now worked for what would become the FDA, helped calculate how to feed soldiers on the front, using the highest possible calories per pound to keep down shipping costs and facilitate transportation. The energy-densest foods turned out to be beef and butter and sugar. Housewives at home were encouraged to lay off the calorie-dense foods in order to save them for soldiers abroad, and calorie tables started being circulated to assist with this patriotic mission. When this voluntary war-time rationing started to be accompanied by “Watch Your Weight Anti-Kaiser” clubs, calories found their ideal métier: weight loss.

A mania for weight loss ballooned after the war, throughout the Great Depression, and up to the present day. With calories as their totem, doctor after advice columnist after Surgeon General trumpeted the importance of losing weight, and, at least since the 1920s, warned of America’s “obesity epidemic.” Things only got worse for the overweight as excuses, such as “glandular problems,” were eradicated from the medical lexicon in the thirties, and during World Wars I and II it was considered downright unpatriotic and “fat-hoarding” to be heavy, to eat things that should be saved for the troops. (This was complicated by the fact that soldiers returning from World War I had developed an appetite for beef, and expected to eat it every day as they had in the trenches. This change in dietary norms, combined with other factors, made “voluntary rationing” fail in WWII: it was replaced by involuntary  restrictions.) Incoming freshmen at Smith College were given “ideal weight” tables upon registration, and newspaper health columnists commented that the most crippling side effect of obesity was probably loneliness, because “nobody loves ‘em” (a Dr. Evans wrote this in a column dated March 9, 1925). Insurance companies circulated the weight tables by which they determined whom to insure in order to encourage potential clients to “reduce,” and penny scales that literally shouted their user’s weight graced every corner; all-in-all, a new era of fat-shaming had begun.

Excess weight is both a symptom of many health problems and the cause of many others. However, the average American is only 6-11 pounds heavier than a generation ago (see Further Reading below); this is not a positive trend and does represent a real concern, but in addition to being exaggerated, American obesity is treated differently than other crises. Cancer and diabetes, too, are on the rise, and probably for some of the same reasons; however, it is much less acceptable to hold cancer and diabetes sufferers wholly responsible for their situation (we tend to blame genetics or perhaps tobacco companies), or indeed ask them to deal with what is a socially generated problem with personal “discipline.” Food companies, like tobacco companies, are just trying to make a buck; calories help them masquerade foods that have been designed to make money for their producers as health foods designed to help the consumer. Unlike tobacco companies, then, food producers sell both the addictive/problem-causing agent, unhealthy food, and the perceived cure, low calorie and diet foods. Nabisco, for example, sells both the Oreo and the Oreo Thin Crisp 100-calorie pack. In fact, a food system and culture that calories themselves helped develop are central causes of a general public ill-health, of which obesity is merely one symptom among many.

The very thing that makes calories such an attractive and effective tool for advocates of weight-loss is what makes them so ambiguous as an aid to healthy eating. Measuring all food by the same standard implies that all food is basically the same, and simply of a variable density. One Snickers bar is exactly equivalent to 55 leaves of lettuce, the ineluctable logic of calories tells us. This is false. Even iceberg lettuce, though long treated as nutritionally negligible, is one of a handful of dietary sources of vitamin D (along with shiitake mushrooms and things like whale blubber; the latter explains why the Inuit, despite living in a zone of limited sunlight, never evolved paler skin) and will aid your digestion. One solitary Snickers bar probably won’t have much effect at all, but it won’t help your digestion, your vitamin B metabolism, tire your jaw or fill you up as much as a ridiculously large salad would. Nonetheless, the sublime draw of simplicity, especially when the number of products in supermarkets has more than quintupled, is almost too strong to resist. Not to mention that calories are, in a sense, effective—if you “burn” (however sketchily approximated by your treadmill, which, I’m here to tell you, is wildly exaggerating) more calories than you “consume” (or, as they called it in a quainter time, “eat”) you will lose weight, at least if you aren’t left so unsatisfied by “low calorie” foods that you snap and eat 18 cookies.

So perhaps the so-called “obesity epidemic” is really a symptom of a more pervasive health crisis: the confusion between “health” and “weight.” Ever since the penny scale and the New York Life Company’s insurance tables, during the past eighty years in which “obesity epidemics” have been ceaselessly trumpeted in America, we have repeatedly confused weight with health. Is weight important to health? Absolutely! However, one can be large (at least to a certain extent) and healthy, or skinny and extremely unhealthy. Correlation is not identity, and while counting calories can help you lose weight, it cannot make you healthy. A public that accepts that Diet Coke is neutral or even beneficial for your health (after all, it contains zero calories! Who cares if it also contains formaldehyde?) has to be cajoled into eating avocados and walnuts, because, gasp, they are very high in calories! As we have both the most overweight and the most weight-conscious society in the world, there is obviously something wrong with our health (and our weight-loss!) methodology.

It is calories and the allure of the quantifiable that have led us down this primrose path. While it is easy as it is to say that we should abandon the calorie and use our common sense, not numbers!, to distinguish healthy from unhealthy food, almost all of us have been trained from earliest youth to distrust our common sense when it comes to food. Part of this is the fault of artificial sugar, which tastes wonderful to small animals (like children) with an evolutionary craving for fruit—even bees and hummingbirds prefer the concentrated fake stuff to the real thing when they have the opportunity. For the rest of it, we are a nation of extremes. If an article touts the benefits of blueberries, we all rush to the store and pledge to eat blueberries every day. Told that potatoes are starchy, and thus, less desirable than, say, whole grains, we abjure them in toto. But, with apologies to Popeye, not even spinach, that quintessential health food, is good for you if eaten every day—in excess, the oxalates it contains can inhibit calcium uptake. Am I saying to quit eating spinach? Absolutely not; merely, all things in moderation. Practically anything can be harmful if eaten to excess, and likewise, nothing is that awful if eaten only occasionally (in the case of some foods, very occasionally indeed). Variety in food eaten and cooking method used (sometimes raw, sometimes boiled, sometimes grilled, etc.), and eating only when hungry and until full, is an easy and natural route to follow that allows us some time away from the calculator and charts.

The fact that books on this theme (i.e. the notion of eating fresh, normal food in reasonable quantities) are never off the bestseller list, combined with the amount of time doctors devote to nutritional advice (knowing what to eat should not be something that requires a doctoral-level degree, unless one has already developed a specific diet-related illness, like diabetes or diverticulitis), goes to show the power of calories. Calories reduce foods to mere numbers to be toted or compared; now books and graduate degrees are required to fill back in knowledge that should be available to everyone, through tradition or common sense. Unfortunately, eating in a way that should be both simpler and more natural is now actually more difficult and complicated—one now has to read books to figure it out!—while eating according to calories only requires basic addition. While writing this article, basically about how calories are stupid, I became subconsciously more calorie-conscious and, while reading about past weight loss trends, I found myself gazing in the mirror and wanting to lose weight! These things have become so embedded in our culture that they are extremely difficult to shake off or avoid, and that in itself is a problem for both physical and psychological health. Perhaps not in the short run, but in the long run, an approach to eating that is conscious but not calorie-conscious, and concerned more with content than density, should make us happier and encourage us to eat healthy things that are also delicious (lentil soup! At least, I think it’s delicious), instead of having to choose between the “healthy” (100-calorie packs) and the delicious. In the short run, though, it takes a little more work.

For their original use, that is, determining the energy density of food, calories are efficacious—let’s ignore, for the moment, that anyone who has ever eaten anything can tell perfectly well what foods are energy dense and what aren’t (pop quiz: what makes you more full, a small orange or a six ounce steak? A head of iceberg lettuce or a wedge of cheese?). Very high calorie foods that also happen to be unhealthy have more effective warning labels attached than simply a few hundred calories. Twinkies never go bad, and Taco Bell “taco meat” has been alleged to contain less than 50% meat. The problem with them is simply not the amount of calories they contain, any more than vegetables are good for you because they contain few calories; vegetables are good for you because they contain essential vitamins, minerals and nutrients that are essential for life, not because they fill you up without fattening you. Plenty of high-calorie foods, like the aforementioned avocado, are good for you, while plenty of low-calorie foods, especially anything that has been modified from its original form to reduce calories, are part of the problem (they can even increase weight, as artificial low-calorie sweeteners often act as an inadvertent appetite booster). I’m not saying that one should never eat unhealthy food (I’m actually eating a Heath bar chocolate chip pecan cookie literally as I type); I’m saying one should not delude oneself that eating a cheeseburger that contains a panoply of known carcinogens and un-researched chemicals will have no ill effect simply because you offset the calorie intake with exercise. It might not make you any fatter, but it is still not good for you.

There’s another factor, in addition to the appealing nature of simplicity, that has encouraged the centrality of calories to American notions of and discussions of health: the incredible power of the food producers and agricultural lobbies in American politics. The government could never get away with recommending people cut down on consumption of cheese or beef; the meat or dairy lobbies would have a fit, and, in fact, often do. As a result, the government has tended, for the past 60 years, to keep its food recommendations vague (eat some dairy, some protein, and lots of carbohydrates! Vegetables of multiple colors are good for you!) or, better yet, completely impartial; when the government merely recommends calorie allotments, it is giving you, the consumer, free rein. The new “MyPlate” system, which has replaced the “Food Pyramid” of my youth (roundly attacked as motivated as much by a national wheat surplus as by any research on the virtues of carbohydrates), encourages one to fill half of one’s plate with vegetables, which is certainly very sound advice. However, that is not the health advice implicit on government labeling; if a candy label told you it was 400% of your daily “fats, oils and sweets” recommendation, or a bag of baby carrots remarked that it was 25% of the “DV” of vegetables (better yet, 50% of orange, beta-carotene containing vegetables?) such truly good advice might further permeate the national psyche. But as long as such advice is relegated to the USDA website and all food packages encourage one to view food items as interchangeable caloric chunks, those tools, while admirable, remain peripheral to the food culture. So that, in a nutshell, is how calories heralded in an era of unprecedented fat-shaming combined with an era of unprecedented ill-health; sure, obesity is part of it, but let’s not forget anorexia, bulimia, malnutrition, vitamin deficiencies, and diabetes while we’re crossing the street to avoid fat people.

Further Reading

For more on the scientific history of the calorie, from Lavoisier to Atwater, see:

“History of the Calorie in Nutrition” by James L. Hargrove, published in the Journal of Nutrition in 2006.

For more on the social history of American diet/diet fads, see:

Yager, Susan. The Hundred Year Diet: America’s Voracious Appetite for Losing Weight. New York: Rodale Books, 2010.

For more on the modern food system and how it got this way (and how messed up it is) see:

Patel, Raj. Stuffed and Starved: The Hidden Battle for the World Food System. New York: Melville House Publishing, 2008. Page 275 features the facts on the figures behind the obesity epidemic.

For more on what foods are actually healthy (as opposed to being merely low or high calorie), the most obvious book suggestion of all:

Pollan, Michael. The Omnivore’s Dilemma. London: The Penguin Press, 2006.

Or, if you want a more unusual and more complicated treatment of what constitutes health, and healthy eating, with a macrobiotic twist, I recommend:

Colbin, Annemarie. Food and Healing. New York: Random House, 1986.

For the USDA’s “Nutrient Database” that companies use to calculate calories in foods, see:

http://ndb.nal.usda.gov/

For more on global cancer rates, see:

http://www.who.int/mediacentre/news/releases/2003/pr27/en/

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