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Why Calories Count: From Science to Politics

Marion Nestle
Malden Nesheim
Copyright Date: 2012
Edition: 1
Pages: 304
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  • Book Info
    Why Calories Count
    Book Description:

    Calories-too few or too many-are the source of health problems affecting billions of people in today's globalized world. Although calories are essential to human health and survival, they cannot be seen, smelled, or tasted. They are also hard to understand. InWhy Calories Count,Marion Nestle and Malden Nesheim explain in clear and accessible language what calories are and how they work, both biologically and politically. As they take readers through the issues that are fundamental to our understanding of diet and food, weight gain, loss, and obesity, Nestle and Nesheim sort through a great deal of the misinformation put forth by food manufacturers and diet program promoters. They elucidate the political stakes and show how federal and corporate policies have come together to create an "eat more" environment. Finally, having armed readers with the necessary information to interpret food labels, evaluate diet claims, and understand evidence as presented in popular media, the authors offer some candid advice: Get organized. Eat less. Eat better. Move more. Get political.

    eISBN: 978-0-520-95217-1
    Subjects: Health Sciences

Table of Contents

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  1. Front Matter
    (pp. [i]-[vi])
  2. Table of Contents
    (pp. [vii]-[viii])
  3. Introduction
    (pp. 1-10)

    When our then-editor at University of California Press, Stan Holwitz, suggested that we write a book about calories, we said yes right away. Consumption of too few or too many calories is an important — arguably themostimportant — cause of public health nutrition problems in the world today. Problems with calories affect billions of people in rich as well as poor countries. Consuming too few calories leads to malnutrition (undernutrition), which makes people more susceptible to infectious disease. The result is stunted growth, misery, and premature death in children and adults. More than a billion people, most of them in...

  4. PART ONE. Understanding Calories:: It All Starts with the Science

    • [PART ONE Introduction]
      (pp. 11-12)

      In thinking about how to begin a book about calories, we kept coming back to the science. Both of us were trained as scientists, Malden in nutrition and biochemistry and Marion in molecular biology and public health nutrition, and we tend to think like scientists. By this we mean that we consider as much of the available evidence as we can as a basis for forming opinions about diets and dieting. Doing this is not as simple as it might appear. Nutrition is an unusually challenging field of scientific inquiry. Human diets and behavior are difficult to investigate. People vary....

    • CHAPTER 1 What Is a Calorie?
      (pp. 13-20)

      In embarking on an entire book about calories, we have to begin at the beginning — what to call them. Calories are units of work or heat, but what they are called depends on who is doing the calling. We think the name inconsistencies can be so confusing that we summarize them in table 1. We believe there is an easier, commonsense way to think about the definition, as we will explain. To get to that point, let’s begin with the official definition used by chemists:

      One calorie is the amount of heat energy needed to raise the temperature of one...

    • CHAPTER 2 The History: From Ancient Greece to Modern Calorie Science
      (pp. 21-29)

      Although it may seem self-evident that food is essential to life, scientists did not have much real understanding about how food energy keeps bodies warm, growing, and functioning until the late 1700s. The earliest understanding of calories as energy released by the interaction of oxygen with food molecules is usually attributed to Antoine Lavoisier, who lived and died in the eighteenth century. Lavoisier’s view of metabolism as an oxidation process — the “burning” of food molecules in the presence of oxygen — still holds true.

      We explain how this works in later chapters, but to jump-start the discussion let’s begin with a...

    • CHAPTER 3 Foods: How Scientists Count the Calories
      (pp. 30-39)

      Because the energy stored in food molecules is the same whether they are oxidized inside or outside the body, scientists can measure the energy value of a particular food to the body by burning it to completion. Nineteenth-century scientists developed calorimeters to measure the total energy stored in foods and in each of their energy-producing molecules: protein, fat, carbohydrate, and alcohol. Note again that cholesterol, vitamins, antioxidants, minerals, and water are not sources of calories. Cholesterol is excreted in bile and not metabolized. Vitamins and antioxidants are present in such small amounts — milligrams or micrograms — that they produce too little...

    • CHAPTER 4 Bodies: How Scientists Measure the Use of Calories
      (pp. 40-48)

      Nineteenth-century scientists were eager to find out how many calories someone might need to maintain basic body functions, activities, and weight. To do so, they had to be able to measure the amounts of heat produced when people were engaged in daily activities. They started by inventing devices — calorimeters — to measure the heat produced by small animals. Later they figured out how to construct calorimeters large enough to house people and farm animals. These “whole-body” calorimeters allowed them to makedirectmeasurements of heat output.

      Studies using even the largest calorimeters required people to be confined to the device, and...

  5. PART TWO. Why You Need Calories:: Survival, Warmth, and Work

    • [PART TWO Introduction]
      (pp. 49-50)

      We devoted earlier chapters to the number of calories in proteins, fats, and carbohydrates; the number of calories from these components in foods used by the body; and the ways scientists arrived at those numbers. We did this to emphasize that scientists can accurately measure calories in food or the body, but doing so requires complicated laboratory equipment such as bomb or whole-body calorimeters or chemical techniques that require isotopes and expensive machines. For convenience, it is much easier to estimate calorie numbers using indirect measurements or calculations. Although calorie estimates are grounded in experiment, some aspects of the use...

    • CHAPTER 5 Metabolism: How the Body Turns Food into Energy
      (pp. 51-56)

      Our colleagues in anthropology are fond of saying “You are what you eat.” By this they mean that food choices reveal a great deal about your position in society — age, family background, educational level, religion, and other such things. If you know what people eat, you can make some pretty good guesses about where they come from, what they believe, and how educated and rich or poor they are. Food choices also differ in the ways they affect health. But the digestive tract makes few such distinctions. Unless you have a genetic or acquired intolerance to certain foods, your digestive...

    • CHAPTER 6 The First Use of Calories: Basic Life Functions
      (pp. 57-62)

      For years scientists have divided the use of calories in the body into three distinct compartments — basal metabolism, the heat (“thermic”) effect of food, and work or physical activity. During much of the twentieth century and continuing into the twenty-first, physiologists have expended a great many of their own calories in thought and action to measure the precise number of calories used to power each of these separate compartments. In this chapter we deal with the energy cost of basic body “housekeeping” functions — the proportionately large number of calories needed to fuel the brain, heart, lungs, kidneys, nervous system, and...

    • CHAPTER 7 The Second Use: Heat Losses while Metabolizing Food
      (pp. 63-68)

      One reason why basal metabolic rates must be measured when you have not eaten for twelve to fourteen hours is that eating itself raises heat production even when you are at rest. Not only that, but it usually takes several hours before your heat production returns to basal levels. You get to choose what to call this effect. In 1902 Max Rubner called it specific dynamic action (SDA). Henry Armsby called it the heat increment. More recent investigators prefer to call it thethermiceffect of food, and we do too. These calories appear to be wasted. They are not...

    • CHAPTER 8 The Third Use: Physical Activity
      (pp. 69-76)

      Physical activities — the normal moving around that you do during daily life and the more intense actions involved in deliberate exercise — promote good health. Using calories to be active is well established to strengthen muscles, help maintain body weight within healthy ranges, reduce risk factors for chronic disease, and make you feel better.

      The amount of physical activity most closely associated with these benefits is a matter of some debate, but most authorities advise you to regularly engage in moderate or vigorous activity for at least half an hour on most days.¹ Bymoderate activity,they mean the equivalent of...

  6. PART THREE. Calorie Intake and Its Regulation

    • [PART THREE Introduction]
      (pp. 77-78)

      It is now time to consider questions about the number of calories really needed in the course of everyday life, the number people are actually consuming, and the ways in which the body controls calorie intake. Because scientists know a great deal about the energy requirements of basal metabolism and physical activities, they have been able to develop equations that give reasonably accurate estimates of the basal metabolic rate and the total energy expenditures of men and women of differing weights, heights, ages, and physical activity levels. These equations have proved to be useful for estimating energy needs under a...

    • CHAPTER 9 How Many Calories Do You Need?
      (pp. 79-85)

      We can’t think of any intuitive way to answer this question. When everything is working the way it should, you don’t need to give calorie requirements a thought. You eat when you are hungry, you stop when you are full, your weight does not change, and somehow it all works out. About all you can do to sense calories is feel full after eating and realize that it takes more energy to work up a sweat than to sit at a desk.

      As to the number of calories you need, they must balance the number you expend. A United Nations...

    • CHAPTER 10 Calorie Confusion: The Struggle to Estimate Intake
      (pp. 86-93)

      As we demonstrated in the previous chapter, studies using doubly labeled water — as close to a gold standard as exists — find that the average nonoverweight adult man needs about 3,050 calories a day to maintain a stable body weight, and the average woman about 2,400. The FDA’s 2,000-calorie standard for food labels is 50 percent lower than the average for men and 20 percent lower than that for women. But many — if not most — Americans are gaining weight. Therefore, they must be eating more calories each day than they need to maintain a stable weight. (How many more? See chapter...

    • CHAPTER 11 Secret Calories: Alcohol
      (pp. 94-100)

      Until now we have ignored the contribution of alcohol to calorie intake, mainly because not everyone drinks spirits, wine, or beer. Also, alcohol is metabolized somewhat differently than the other energy-producing molecules in food. But beer, wine, and hard liquor most certainly provide calories. For the most part these calories are empty. Alcoholic beverages typically contain no nutrients or so few that they are hardly worth mentioning.¹

      For the discovery of the calorie value of alcohol, we must turn yet again to Wilbur Atwater. Until 1897 his publications of food composition did not list alcoholic beverages. That year, he and...

    • CHAPTER 12 Calorie Regulation: The Body’s Complex Weight Management System
      (pp. 101-110)

      A daily intake of more than 2,000 calories adds up to nearly a million calories a year, yet many people — without consciously doing anything about it — remain at about the same weight throughout their entire lives. Input and output can vary by hundreds of calories from day to day without causing any noticeable long-term change in body weight. Over time, something must be controlling calorie intake and balancing it against calorie expenditure with remarkable precision. But what?

      How calorie regulation works is a question that thoroughly intrigues researchers, especially now that obesity has gone global. When discussing their work, scientists...

  7. PART FOUR. Too Few Calories

    • [PART FOUR Introduction]
      (pp. 111-112)

      People do not usually choose to eat too few calories to support their energy needs. When they do, they feel hungry. The pangs of hunger are acute enough to make anyone want to eat, and right away. Chronic hunger is most often forced upon people by poverty, war, or natural disasters. But sometimes people who have plenty of food available choose not to eat. They diet to lose weight. They fast for religious or political reasons. Or they deliberately restrict calorie intake in an attempt to live longer. In this part of the book we zero in on the physiological...

    • CHAPTER 13 Starvation and Its Effects on the Body
      (pp. 113-120)

      The immediate response to a need for more calories is hunger for food. Feelings of hunger may be mild or intense and can range from slight irritation to extreme agony. Chronic hunger is a miserable experience, but the degree to which it induces mental misery depends greatly on whether the calorie deprivation is voluntary or forced. Although people with plenty of access to food may say “I’m starving” when they haven’t eaten for a few hours, the difference between voluntary and forced hunger is so critical that scientific publications and newspaper articles often describe them in different words. Fasting refers...

    • CHAPTER 14 Individuals, Communities, Nations: Calories and Global Hunger
      (pp. 121-129)

      Late in 2010 the United Nations’ Food and Agriculture Organization (FAO) announced what passes for good news on the international scene. By its estimation, “only” about 925 million people throughout the world were suffering from chronic hunger. This number, enormous as it is, represented a decline of nearly 10 percent from the previous year.¹

      How did the FAO arrive at this count? In a word, calories.

      To make such estimates, the FAO asks each of its 192 member countries to provide three kinds of statistical information:

      The amounts of all food commodities produced, used for seed and animal feed, wasted,...

    • CHAPTER 15 Could Restricting Calories Prolong Human Life?
      (pp. 130-136)

      Calorie deprivation, as we have seen, is difficult to endure and induces premature death in children and adults. Surely it should be avoided. But in 1935 Cornell professor Clive McCay and his colleagues noticed that when they fed diets deficient in nutrients to mice and rats, the animals grew more slowly. The researchers wondered whether the slowing down of early growth might affect how long the animals lived and decided to investigate that question. They established a feeding protocol for just-weaned male laboratory rat pups. For a few weeks they gave the baby rats in sequence:

      enough calories to survive...

  8. PART FIVE. Too Many Calories

    • [PART FIVE Introduction]
      (pp. 137-138)

      In the next chapters we address questions about what happens when you eat more calories than you expend, put on weight, become overweight or obese, and then try to take the weight off. Overweight and obesity are nowglobalphenomena. In many countries the numbers of obese people exceed the numbers who are undernourished and hungry. The importance of obesity as a worldwide public health problem has encouraged researchers to investigate trends and their causes and determine the levels of overweight and obesity that increase health risks. In our attempt here to define the number of excess calories that must...

    • CHAPTER 16 An Introduction to Obesity
      (pp. 139-143)

      If you habitually eat more calories than you expend, you will gain weight, and most of that weight will be in the form of fat. A pound of body fat tissue contains about 3,500 calories. You can work this out using the Atwater Value: 9 calories per gram times 454 grams per pound. Even without a calculator, it should be obvious that this sum comes to more than 3,500 calories. But fat tissue contains only about 85 percent fat; the rest is water, protein, and other such things. Multiplying 4 times 454 by 0.85 gives you a number that conveniently...

    • CHAPTER 17 Calories and Weight Gain: Another Complex Relationship
      (pp. 144-149)

      Increases in body weight are easier to measure than increases in body fat, but excessive body fat is the cause of metabolic problems. If you eat too many calories for the number you expend, most of them will end up as body fat. Fatty tissue is an ideal place to store calories, not least because its capacity seems unlimited in some people. Very obese people can accumulate very large amounts of body fat, and magazines delight in publishing articles about people who weigh 1,000 pounds or more.¹

      What complicates discussions of body fat is that it is good to have...

    • CHAPTER 18 Do Excess Calories Make Some People Gain Weight Faster than Others?
      (pp. 150-157)

      Everyone knows people who are not especially athletic but seem to be able to eat anything in front of them and never gain an ounce. Are they not telling the truth about what they eat? Or do they really burn off calories more efficiently than everyone else? Some people seem to be able to lose weight effortlessly, while for others it is an interminable struggle. Here we take up the matter of individual variation in response to excessive calorie intake.

      The overfeeding studies described in the previous chapter answer this question to some extent. In response to eating thousands of...

    • CHAPTER 19 Are All Calories Created Equal?
      (pp. 158-164)

      Whether the particular mix of protein, fat, and carbohydrate in a diet makes any difference to weight loss is not a new question. In 1964 a group from the Institute for Medical Research in Oakland, California, examined precisely this issue in case studies of five obese patients who resided in a hospital metabolic ward. The researchers fed each patient a liquid-formula diet containing the same number of calories per day — either 800, 850, or 1,200, depending on the patient, for ten weeks or more. Every three or four weeks the investigators changed the formula to vary its content of protein...

    • CHAPTER 20 Do Some Kinds of Diets Work Better than Others?
      (pp. 165-174)

      One problem in studying the effects of dietary composition is that it is not possible to vary the proportion of one component without changing the others. At the extremes of weight-loss diets, the Atkins and South Beach diets are low carbohydrate but high fat, while the Ornish diet is low fat, high carbohydrate.¹ To compare the effects of such diets outside metabolic wards, researchers must deal with study subjects whose dietary and other behaviors are not easily controlled.

      Investigators do everything they can to encourage compliance with study protocols. But they confront a major challenge: telling free-living people what you...

  9. PART SIX. The Politics of Calories:: A Closer Look

    • [PART SIX Introduction]
      (pp. 175-176)

      In previous sections we have explained how politics — as well as science — affects views of the role of calories in the diets of individuals and groups. Of course calories are affected by politics. As with everything else having to do with food and nutrition, many different groups have a stake in how calories are marketed, perceived, labeled, and promoted. The chapters in this last section deal with specific aspects of the social and political environment of calories, beginning with the ways in which this environment has changed. We view the results of these changes, many of which occurred as inadvertent...

    • CHAPTER 21 Today’s “Eat More” Environment: The Role of the Food Industry
      (pp. 177-185)

      Weight gain, as we keep saying, is caused by eating more, moving less, or doing both. Rates of overweight and obesity began to rise sharply in the United States in the early 1980s. Did Americans start becoming less active at that time? Did they begin to eat more? Or, as is widely believed, did both things happen simultaneously? Let’s take a look.

      Practically anyone you ask will tell you that people in general and kids in particular are less active now than they were in recent decades. Kids hardly ever take physical education classes, walk or ride bicycles to school,...

    • CHAPTER 22 More Calorie Confusion: Portion Distortion, Health Halos, and Wishful Thinking
      (pp. 186-191)

      For many years Dr. Lisa Young, an expert on portion size and author ofThe Portion Teller(Crown, 2005), has taught an introductory nutrition class at New York University. As a favor to us, she agreed to devote some time on the first day of class to asking students about their basic understanding of food calories. Among her questions were these: How many calories are in an 8-ounce soda? How many calories are in a 64-ounce Double Gulp soda?

      We did not expect beginning students to know the number of calories in an 8-ounce soft drink, and most did not....

    • CHAPTER 23 Calorie Labeling: Science and Politics
      (pp. 192-200)

      One way to help people learn about calories is to list them on food labels, but mandatory calorie labeling is relatively recent in the United States. During much of the twentieth century the FDA officially allowed nutrition information on food labels only when food products were meant for the treatment of specific diseases or other “special dietary uses.” We sayofficiallybecause this restriction did not stop food companies from displaying information about added nutrients — and occasionally calories — when it helped to market their products. The FDA permitted them to do this as long as the labels did not display...

    • CHAPTER 24 Alcohol Labels: Industry vs. Consumers
      (pp. 201-208)

      Regulating alcohol, as we explained in chapter 11, is about tax revenues, not health. The end-of-Prohibition law passed in 1935 made the Treasury Department responsible for labeling hard liquor and most wines and beers. The department’s Alcohol and Tobacco Tax and Trade Bureau (TTB) requires calories to be labeled only on beers marketed aslight.¹ Other alcoholic beverages do not have to list calories, and most do not. If you want to know the number of calories in your drink, you can measure its volume and assume that standard servings of wine (5 ounces), light beer (12 ounces), and the...

    • CHAPTER 25 Will Calorie Labels Help Fight Obesity?
      (pp. 209-216)

      By the early 2000s federal health officials recognized that rates of obesity were rising rapidly, and they began looking for ways their various agencies could encourage individuals to take personal responsibility for controlling calorie intake. In this chapter we review U.S. efforts to educate the public about calories through better food labels and through city, state, and national laws requiring restaurants to post calorie information.

      In 2003 the FDA created an internal Obesity Working Group (OWG) to assess how the agency might educate consumers about calorie balance. The OWG members, all FDA professional staff, were impressed by “the scientific fact...

  10. Conclusion: How to Cope with the Calorie Environment
    (pp. 217-226)

    We said at the outset thatWhy Calories Countis not a dieting or weight loss book. Instead, we wrote it to equip you with tools you might find useful for evaluating diet claims and developing your own weight management strategies for gaining or losing or just staying where you are. From our review of the research, we are convinced that calories count. If you want to lose weight, you really do need to eat less and move more than you have been doing. But let’s be clear: you must also eatbetter,which means making healthier food choices.


  11. APPENDIX ONE. Selected Events in the History of Calories, 1614–1919
    (pp. 227-229)
  12. APPENDIX TWO. The Respiratory Quotient (RQ)
    (pp. 230-232)
  13. APPENDIX THREE. Frequently Asked Questions
    (pp. 233-238)
  14. NOTES
    (pp. 239-270)
    (pp. 271-272)
    (pp. 273-274)
    (pp. 275-276)
  18. INDEX
    (pp. 277-288)
  19. Back Matter
    (pp. 289-291)