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1.6: Food for Life

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    What factors affect what I eat?

    You know the mechanics of digestion, and you know what you should eat. But there often seems to be a difference between what we all know is right to eat and what we often end up eating. Let's take a look at what makes people eat and stop eating, why people eat what they do, and some of the many factors that affect their dietary choices. In this section you will also learn about diets and eating disorders.

    Hunters, Gatherers, and the Earliest Chefs

    Food is necessary to life. Hunger drives us to seek out food. Over the millennia, how people seek out food has changed. Two million years ago people were vegetarians and scavengers. Their lives revolved around the acquisition of food. As people learned to hunt, they began hunting in small bands. They would follow herds for hundreds of miles, or they would follow vegetation and small animal life from highlands to lowlands depending on the season. Today, we have the convenience of the local grocery store and our own gardens, if we choose. The bottom line is that we have more choice about how we get food and about what we eat.

    what do you think?

    Why did our ancestors begin cooking foods?

    ​​​​​​​In addition to more food choices, how we prepare foods has changed a lot from the days of the earliest humans. It is estimated that humans first began cooking somewhere between 500,000 B.C. and 75,000 B.C. Cooking foods dramatically changed the eating experience. Not only did cooking meats and vegetables change the taste and consistency of the food, but it also improved the nutrient value of some foods. Over time, humans also figured out how to raise plants and animals, how to refine grains and sugars, and how certain cooking and refrigeration methods enhanced a food's longevity. By the mid-1800s, new food storage containers such as cans emerged. These new storage containers provided an inexpensive and effective way to prepare and preserve different foods. The industrial revolution brought new methods of transporting foods to the food industry. It also provided the food industry with storage containers of various sizes. The importing and exporting of canned processed foods became a big business.

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    Figure 5.1 A cookout can be fun. Just remember to clean up, make sure the fire is completely out, and follow the area rules.

    The invention of refrigeration replaced the tedious and cumbersome task of cutting and transporting ice from frozen lakes to ice houses in cities. Refrigeration made it easy to store and transport fresh, frozen meats, as well as other foods, around the world. Packaged frozen foods became available in grocery stores only in the middle of the 1900s when your grandparents were children.

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    Figure 5.2 A 19th-century icebox (top photo) actually used ice to keep food cold. Today we use refrigerators, as shown in the bottom photo.

    What is so important about food preparation inventions and the exporting and importing of food? They changed what people ate. The fact that explorers, both on land and sea, could have healthy stores of food available when the natural food sources were scarce changed their health for the better. City dwellers suddenly had many more choices-bananas from the West Indies, fresh fish and meat instead of pickled herring or dried buffalo meat, and a host of fruits and vegetables from other parts of the world. All these different foods provided Vitamins, minerals, fats, and carbohydrates on a regular basis instead of on an occasional basis.

    mini activity

    Food Choice Make a list of the foods you have eaten in the last 24 hours. For each food item, indicate why you selected it. Share your choices and reasoning with the class.​​​​​​​

    ​​​​​​​Feeling Hungry

    What makes you hungry? When your stomach is empty, you want to fill it. This feeling of needing to eat comes from many places. Your empty stomach sends messages to your brain. Other parts of your digestive system send messages to your brain too. Nerves and hormones tell your brain about how your digestion is going and when your intestines are ready for another meal. The brain also monitors how much sugar is in your blood. Your brain sorts out all of the messages. Your brain also tells you to eat all by itself. This is why thinking about food, smelling food cooking, watching a TV ad, and hearing a friend's suggestions can get your mouth watering. Even eating can make you want to eat more when food tastes really good. The food industry influences us through advertisement. It is impossible to pass through a town without seeing fast food restaurants, billboards for restaurants, or even smelling the cooking from a local eatery.


    Many things can affect your appetite. How many can you think of? What situations make you hungry? What situations make you lose your appetite? Which of these things do you have control over?

    ​​​​​​​Why do you stop eating? There are many reasons. The main reason is that you feel full. Your stomach and intestines send signals to your brain saying you're full. Scientists really don't fully understand all of these signals or their timing. But usually about 20 minutes after you start eating, you feel full.

    journal writing

    The next time you are waiting for and then eating a meal, think about the role your five senses play in the experience. Write a poem, song, or story about eating as a sensory experience. Can you make someone salivate just listening to your poem, song, or story?​​​​​​​

    ​​​​​​​It's not just a matter of how much food you eat in 20 minutes. It simply takes that long for your digestive system to tell your brain to stop eating. This slow signal from the guts to the brain can be a problem for some people. People who eat fast can put more calories into their stomachs in 20 minutes than they need. As a result, they overeat without realizing it. That's why you should try to eat more slowly rather than “eating and running.” The body needs time to begin digesting and absorbing what you have eaten before it can give signals to the brain that cause a feeling of being full.

    Is there anything else that tells you not to eat? Yes. Your brain tells you not to eat, too. You lose your appetite when you get sick. Some people don't eat when they're afraid or depressed or worried about something. Someone who's just lost a friend or is upset may not want to eat. This person may even lose weight. If someone you know doesn't eat for these reasons and loses weight, talk to that person about seeking help. Many problems are too difficult for just one person to handle.

    Exercise can be an appetite stimulant and an appetite suppressant. When you work out, the body tells the brain not to think about food. The hormones and chemicals your body produces during exercise turn down your appetite. This is one reason doctors try to get overweight people to exercise. Exercise burns fat and uses extra calories. But exercise also tells the brain not to let you eat too much. After exercising, you may feel very hungry, but often hungry for healthy foods instead of foods high in sugar or fat.

    Factors Affecting What We Eat

    What are some of the factors that affect what we eat? There are three general factors that influence what and how much food we eat-culture and family, availability and cost, and education.

    Culture and Family

    How do people choose what to eat? Food must meet the body's need for nutrients and energy. But the food you eat is usually what you want to eat, too. Different people eat different foods. Along with cultural diversity comes food diversity. Some people, such as many vegetarians, choose foods to improve their health. But most people choose what they eat because of their culture, not because of nutrition. You learn to eat the foods that your family likes. Often, you choose foods to fit your culture.

    what do you think?

    Do you enjoy going to a friend's house for dinner? Why or why not? What are some of the factors that make it both enjoyable and sometimes a little stressful?​​​​​​​

    ​​​​​​​Lots of ideas exist about how food traditions started. For example, it has been suggested that people who lived in cold, damp parts of the world (northern Europe) developed a tradition of eating rich, fatty foods that helped them put on fat to keep them warm. Some people think that spicy foods became preferred in tropical climates because they stimulated sweating and drinking of liquids, which helped cool the body. Another idea about spices is that they helped prevent growth of microorganisms in food.

    It is interesting to note how different cultures have developed similar ways of creating balanced diets with regionally available foods. For example, in India, people may eat lentils with flat bread made of yeast. However, in Mexico, people may eat beans with tortillas. In China, a dish of stir-fried vegetables with rice is similar to a traditional dish in Morocco called couscous, made of steamed wheat and vegetables. In this country, we are fortunate to be able to sample the foods of many cultures.

    what do you think?

    Explain why some people have temporary digestive upsets when they move from one region of the United States to another or from one country to another.​​​​​​​

    ​​​​​​​Availability and Cost

    One big factor affecting your diet is what foods are available and how much they cost. Food availability has shaped many civilizations. The availability and price of foods have started wars and expanded empires. For example, the price of tea was a factor that led to the American Revolution. The British Empire grew dramatically in the 16th and 17th centuries in pursuit of foods from the Americas and spices in India.

    Today most Americans have a lot of choice. Unfortunately, many do not have the means to buy all the food they need. Hunger and malnutrition are a huge problem worldwide. The worldwide figures on malnourished people are astounding. According to the Food and Agriculture Organization (FAO), 841 million people are chronically undernourished. Of these, 200 million are children under 5 years of age who suffer chronic protein and energy deficiencies. These children will probably never recover completely even under ideal circumstances. Malnourishment happens for several reasons. Malnourished individuals may live in a country too dependent on one food source. For example, the people of Indonesia get most of their calories from rice, and the people of the Democratic Republic of the Congo get most of their calories from cassava. Rice or cassava alone cannot provide all the nutrients and energy that are needed. Another reason is that food production is underdeveloped in some parts of the world, which causes a dependence on other countries for food supplies.

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    Figure 5.3 This map of the world illustrates the location of North and Sub-Sahara Africa, Asia and the Pacific, the Middle East, North America, Central America, South America, and the Caribbean. See the Did You Know? on this page for foods in these regions.

    did you know?

    What do people grow and eat in some other parts of the world? Here are some examples of regional foods. Sub-Sahara Africa-cassava, yams, maize, plantains, and bananas Asia and the Pacific-rice, wheat, maize, and sweet potatoes South America and the Caribbean-maize, wheat, rice, and potatoes Middle East/North Africa-wheat, rice, maize, and potatoes The source of this list is The Consultative Group on International Agricultural Research (Home Page): Twenty Years of Food Crop Improvement in Developing Countries.


    journal writing

    If there is so much food in the world, why are some people malnourished?

    You have been appointed by the president to a commission on hunger. The commission's task is to come up with solutions to this country's hunger problems. After reading hundreds of reports and studies, your commission has gleaned the following facts.

    • Millions of people in the United States are malnourished.
    • The United States is one of the wealthiest countries in the world.
    • Farmers are paid by the government to NOT produce some foods because we have so much in storage (for example, wheat).
    • The people most affected by malnutrition are pregnant women and children.
    • The problem doesn't seem to be food availability. The real problem seems to be cost, distribution, and education.

    Write your four best suggestions for feeding people in this country who are malnourished. Make sure you explain how your solutions address the facts about the causes of malnutrition, cost and distribution of food, and education for healthy diets. Discuss your suggestions in class. Are there some ideas that have occurred to many students? Which ones would be easiest to implement?


    journal writing

    Design an advertising campaign promoting healthy eating. Your campaign might include songs, posters, flyers, newsletters, commercials during lunch breaks, and more. Be creative!​​​​​​​


    Many people, from the wealthy to the most impoverished, don't know enough about nutrition to eat well. Malnutrition is not a condition restricted to the less well off. People may become malnourished over time because they make choices to eat a diet that lacks adequate amounts of the six nutrients. Knowing about food and what it can do for you helps make the many choices we have in this country clearer. After you finish reading this text, what will you choose to eat for lunch?

    Dieting and Diets

    For one reason or another, some people choose to eat certain types of foods and not others. Sometimes these choices affect one's lifestyle. Let's take a look at a few diet choices, and why they may or may not work for you.

    Vegetarian Diets

    Vegetarian diets rely on plants for protein and energy. Vegetarians avoid meat, but some vegetarians eat milk, milk products, and eggs. Vegetarians do not eat meat for reasons of health, reverence for animal life, religion, ecology, or other reasons. Some vegetarian diets can be very healthy. In other words, they provide adequate calories and nutrients. However, other vegetarian diets may supply too few calories and not enough protein and minerals such as calcium and iron. If you choose to eat a vegetarian diet, you need to be very careful about getting all of the nutrients you need. Remember that specific plant foods do not contain all of the essential amino acids, so vegetarians must select an appropriate mixture of foods to get all essential amino acids.

    Fad Diets

    Fad diets are common. People can choose foods because of experiences described in a book, promoted by a TV personality, or based on what their friends eat. Some people may eat only fruits, honey, nuts, and olive oil. Others may not eat processed foods and avoid the three whites-sugar, flour, and salt. Some people believe certain foods cause disease and leave them out of their diet. Before you go on any diet for any reason, you should check with someone who knows about good nutrition. A proper diet means eating the right amounts of the right foods. You can do a lot of harm to yourself by eating the wrong foods and creating bad habits that are difficult to break.

    Food Problems-Starvation, Obesity, and Food Addictions

    A major food problem in America and the world is malnutrition. Inadequate food intake by choice (fasting or diets) or necessity (poverty, politics, and famine) can cause illness. What are some of the things that happen to your body if you don't eat or you don't eat enough calories?

    A condition known as marasmus is one type of starvation. Marasmus happens in babies who eat too few calories. They don't gain weight; they lose it. The babies become thin and frail. Their skin gets dry and crinkled, because their bodies use up the fat under the skin for energy. Too few calories can result in diarrhea. However, people often do not give babies with diarrhea enough water and salt. They think the babies have too much water in them already, considering the loose bowel movements. The babies can become dehydrated and die.

    Children who do not eat enough protein do not have the amino acids their cells need to continue to grow and divide. This protein deficiency illness is called kwashiorkor. Kwashiorkor is the most serious and common type of malnutrition in the world today. Kwashiorkor means “a child that no longer is suckled.” Kwashiorkor occurs most often in four-or five-year-olds in developing countries. The children get tired, don't eat, develop skin problems, and have weak muscles. They have swollen bellies and feet. Many of these children die or become mentally retarded, because their brains do not develop properly without protein in their diets.

    did you know?

    • The hearts of overweight people must work harder to supply nutrients and oxygen to all their cells. For every pound of excess weight, your heart has to push blood through several more miles of blood vessels!
    • Obesity increases the level of fat and cholesterol in the blood.

    ​​​​​​​Obesity is another food problem. Obesity is most often the result of overeating. Being about 20% or more over your ideal body weight is called obesity. Most obese people eat more calories than they use each day. Their bodies store the extra calories as fat. Genetics can influence obesity. Many obese people come from families with overweight parents. Scientists have identified genes that may contribute to obesity, and they are continuing efforts to learn more about the connections between genetics and body weight.

    Obesity and being overweight is common in children as well as adults. Middle-aged adults who are overweight have about three times the risk of having a fatal heart attack as adults who are within the normal weight range for their height.

    Obese adults often became obese in childhood or during adolescence. Often they do not exercise very much, but it is not easy to know if the lack of exercise contributes to obesity or if obesity discourages the individual from exercising. It is thought that obesity may be due to the brain not receiving the signals that turn off appetite. However, studies of obese people show that they often adapt well to certain weights. They burn more of the extra calories as heat if they eat more than they need to maintain their weight, and their bodies get more fuel efficient if they try to eat fewer calories. Obesity is caused by several factors such as overeating, inactivity, genetics, metabolism, and your body's set point (your ideal weight). If a person cuts caloric intake, the body thinks it is starving and becomes more efficient. So dieting is not easy. Obese people can cut back their food intake and not lose weight.

    Many obese people worry about being heavy. Gaining the extra pounds is so much easier than losing weight. Many people try to diet and fail. Eighty to ninety-percent of all people who try to lose weight by dieting eventually gain the weight back. Some dieters have success losing weight and keeping it off. These successful dieters change the way they think about food and make careful choices about what they eat for the rest of their lives. Gaining and losing weight over and over again is worse than staying at one weight.

    Eating Disorders

    There are two major eating disorders involving food obsessions. They occur most often among teenagers and young adults and more often in females than in males. One is called anorexia nervosa. People with this disorder eat a very small amount of food. Anorexic people are dangerously underweight, but they think they are overweight. They often exercise excessively to lose weight and to suppress their normal urge to eat. Anorexia can cause malnutrition, loss of body fluid, and vitamin and mineral deficiencies. If an anorexic is untreated, severe health problems and death can result.

    Another eating disorder is bulimia. People who suffer from bulimia regularly overeat, or “binge,” and then use laxatives or force themselves to vomit to prevent absorption of food in the intestines.

    Learning about food, eating behaviors, and eating disorders can help you make healthier eating choices for yourself. What other factors affect your overall health and the health of your digestive system?


    What are some things that happen to your body if you don't eat for several days? For several weeks?

    ​​​​​​Activity 5-1: Can You Become Obsessed with Food?


    Eating well and staying fit is important. But how much is too much? Why do some people become obsessed with their weight? Why do they think they're so fat that they must starve themselves? Why do some diet until they become sick or even die?


    • Video clip or video film titled Fear of Fat (or information on anorexia nervosa and bulimia)
    • Assorted magazines
    • Activity Report


    Step 1 Watch the videotape provided. Then discuss the following questions with your group.

    • What issues are responsible for eating disorders, a focus on weight, and dieting?
    • What conditions may lead to eating disorders?
    • What do people in the video feel about the need to be thin? How much are you influenced by the media and fashion, by friends, and by the opposite sex?
    • Do we know why someone crosses the line between dieting and an eating disorder? At what point would you start to worry about a friend?
    • Although males are not as often afflicted with eating disorders, their female friends, girlfriends, and sisters may be. What would you do if you suspected someone you love or care for has an eating disorder?

    Step 2 Analyze a magazine to see if you find evidence of the pressures mentioned in the film.

    • Study the ads and articles. What does the magazine say to people about eating, their body, and weight?
    • Does the magazine send different messages to women than it does to men?
    • What effect might constant exposure to these magazines and similar media (TV, billboards) have on people?

    Step 3 As a group, redesign one of the ads in the magazine so that it provides healthy signals about males and females.

    • What images will you change?
    • What content will you change?

    Review Questions

    1. Why do people eat?
    2. What are some ways to control your appetite?
    3. Diets are different in different cultures. What are some of the reasons people choose different foods?
    4. Why are fad diets so dangerous to your health?

    This page titled 1.6: Food for Life is shared under a CC BY-NC license and was authored, remixed, and/or curated by CK-12 Foundation via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.