Obesity: battling a national health epidemic.About 59 million Americans are suffering from a disease. This illness sneaks into peoples' lives, and it grows on them as they perform daily routines such as eating lunch. But once this disease takes hold of a body, it could put a person at risk for heart disease and other serious medical complications. It could also cause a person to develop social problems, including poor self-esteem. This disease--which has reached a record high number of people in the U.S.--is called obesity, or having an excessively high level of body fat. What is the cause of the nation's expanding waistline? "Obesity is a very complex disease that involves many factors," explains Myles Faith, an obesity researcher at the University of Pennsylvania (body, education) University of Pennsylvania - The home of ENIAC and Machiavelli. http://upenn.edu/. Address: Philadelphia, PA, USA. . So far, scientists have identified obesity-causing factors ranging from the way people eat to how they spend their pastimes to genetics (heredity heredity, transmission from generation to generation through the process of reproduction in plants and animals of factors which cause the offspring to resemble their parents. That like begets like has been a maxim since ancient times. ). And with approximately 300,000 people dying from obesity-related complications each year, an all-time high, scientists are determined to help find solutions that will stop this disorder. DEFINING OBESITY It takes more than a glance to determine if a person is obese. That's why scientists measure a person's Body Mass Index (BMI BMI body mass index. BMI abbr. body mass index Body mass index (BMI) A measurement that has replaced weight as the preferred determinant of obesity. ), a mathematical formula that calculates a person's weight adjusted for his or her height. (For more on the BMI, see Web Extra, p.20.) If the BMI falls within a specified range, (25 to 29.9 kg/[m.sup.2]), an adult is considered overweight. For adults, if the BMI is above the overweight range (over 30 kg/[m.sup.2]), the adult is likely considered obese. For people under the age of 20, scientists categorize the BMI differently. They use a chart of BMI ranges that's specific to the person's age and sex. And these ranges do not include a category for obesity. That's because growing boys accumulate fat differently from growing girls. Additionally, developing bodies have ever-changing fat levels. "So we talk in terms of 'underweight,' 'normal weight,' 'at risk of overweight,' and 'overweight,'" explains Michele Maynard, an epidemiologist (scientist who studies rates of diseases within a population) at the Centers for Disease Control and Prevention Centers for Disease Control and Prevention (CDC), agency of the U.S. Public Health Service since 1973, with headquarters in Atlanta; it was established in 1946 as the Communicable Disease Center. (CDC See Control Data, century date change and Back Orifice. CDC - Control Data Corporation ). Scientists have found strong evidence that people who are overweight as kids and teens are likely to remain overweight or become obese in adulthood. Of particular concern: Since the 1980s, the number of overweight U.S. children between ages 2 and 11 has more than doubled. Even more staggering: In adolescents between ages 12 and 19, the number has more than tripled (see graph, p. 19). "We've also been seeing children and adolescents with increased frequency of type 2 diabetes type 2 diabetes n. See diabetes mellitus. (blood-sugar disorder) and high blood pressure," says Maynard. "These are conditions once primarily associated with adults." Why are so many bodies now tipping the scales? BIG QUESTIONS Like a machine, the body needs fuel to operate. When you eat, your body converts that food into energy. And what your body does not use for fuel is stored as reserve--fat. "Obesity is caused by an imbalance between energy input and energy output," says Maynard. That means, when anyone consumes more calories (energy units in food) than he or she is able to use, or expend, the body is likely to gain fat. But every person's metabolism (chemical reactions This is the 18th episode of television drama Men in Trees. It originally aired on June 25, 2007 on the TV2 network in New Zealand as a continuation of season 1. Recap Marin and Cash have a stew cook off, she admits his is better than hers. in the body that change food into energy) is different (see diagram, p. 20). And the mystery of why some people tend to pack on fat easier than others has led scientists to search for clues. "We believe that genes (units of hereditary information) play a major role in obesity," says Shirly Pinto, a biologist at Rockefeller University Rockefeller University, philanthropic organization in New York City, founded 1901 as the Rockefeller Institute for Medical Research by John D. Rockefeller for furthering medical science and its allied subjects and to make knowledge of these subjects available to the . In 1994, scientists at Rockefeller University made a breakthrough: They discovered that fat cells produce an appetite-controlling hormone (function-controlling chemical), which they named leptin Leptin A protein hormone that affects feeding behavior and hunger in humans. At present it is thought that obesity in humans may result in part from insensitivity to leptin. . This hormone keeps people at a healthy weight. It signals a brain region responsible for maintaining weight levels--the hypothalamus--information on how much fuel the body needs. In other words Adv. 1. in other words - otherwise stated; "in other words, we are broke" put differently , leptin sends out the "I'm full" message. When you have fewer fat cells, less leptin is produced, signaling you to eat more. And with more fat cells, leptin levels increase, signaling you to eat less. How does leptin relate to obesity? "In most cases, obese individuals have leptin levels that are higher than normal," says Pinto. "In a sense, they should stop eating. But they don't." Scientists believe that some obese people may have genetic differences that cause their bodies to be resistant to leptin's messages. Since leptin's discovery, scientists have found other hormones that are involved in how the body perceives food. Could hormone-regulating, fat-fighting medicines result soon? It's too early to tell. How these natural hormones work alone--much less, how they interact with each other--is still unclear. "Scientists are just starting to piece this puzzle together," says Pinto. Even if some people have genes that make them more susceptible to becoming obese, that does not fully explain why the number of obese Americans has recently sky-rocketed. Scientists point to today's lifestyles as a big part of the problem. MODERN PROBLEMS "Americans live in an environment that favors a sedentary lifestyle
Sedentary lifestyle is a type of lifestyle most commonly found in modern (particularly Western) cultures. It is characterized by sitting or remaining inactive for most of the day (for example, in an office. and an over consumption of food," says Maynard. And technological advances are partly to blame. Today, from transportation to entertainment to work tools, "we desire what's convenient," says Faith. "We have cars, TV, the computer--but they are major reasons why Americans lead such an inactive lifestyle." For example, according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. the U.S. Department of Health and Human Services Noun 1. Department of Health and Human Services - the United States federal department that administers all federal programs dealing with health and welfare; created in 1979 Health and Human Services, HHS , one quarter of U.S. children between ages 8 and 16 spend at least four hours a day watching TV. To control weight and fat levels, the CDC recommends that teens perform at least one hour of moderately intense physical activity every day. "Short bouts of various activities count toward meeting this recommendation. Even raking the lawn or taking the stairs require you to expend energy," says Maynard. A sedentary lifestyle is made unhealthier by poor food choices. Today, people consume a lot of pre-packaged and "fast" foods, which tend to be high in fat and calories. And portion sizes have increased over the years (see chart, left). Maynard suggests that teens learn about appropriate serving sizes and replace high-caloric snacks with fruits and vegetables. By overcoming obesity, people would reap colossal medical and social benefits. THE SKINNY ON OBESITY The endocrine system endocrine system (ĕn`dəkrĭn), body control system composed of a group of glands that maintain a stable internal environment by producing chemical regulatory substances called hormones. is a complex network that regulates the body through function-controlling chemicals called hormones. Scientists are finding that certain hormones are linked to obesity. HORMONES AND OBESITY Two hormones, leptin and ghrelin, play an important role in obesity. Leptin Leptin is secreted into the bloodstream by fat cells found in the stomach. Leptin signals the brain's hypothalamus hypothalamus (hī'pəthăl`əməs), an important supervisory center in the brain, rich in ganglia, nerve fibers, and synaptic connections. It is composed of several sections called nuclei, each of which controls a specific function. to secrete secrete /se·crete/ (se-kret´) to elaborate and release a secretion. se·crete v. To generate and separate a substance from cells or bodily fluids. hormones that suppress hunger. [ILLUSTRATION OMITTED] Ghrelin Ghrelin is secreted into the bloodstream by stomach glands. It signals the hypothalamus to secrete hunger-stimulating hormones. When people diet, ghrelin levels rise and leptin levels fall. Appetite increases, making it harder to lose weight. [ILLUSTRATION OMITTED] WEIGHT PATROL KEY PLAYERS OF THE ENDOCRINE SYSTEM Brain Controls at least 40 neurotransmitters Neurotransmitters Chemicals within the nervous system that transmit information from or between nerve cells. Mentioned in: Bulimia Nervosa, Impotence, Pain, Withdrawal Syndromes (brain chemicals) that regulate eating. Food releases the "pleasure-causing" chemicals dopamine dopamine (dōp`əmēn), one of the intermediate substances in the biosynthesis of epinephrine and norepinephrine. See catecholamine. dopamine One of the catecholamines, widely distributed in the central nervous system. and serotonin in the brain. [ILLUSTRATION OMITTED] Hypothalamus A brain region that fields and interprets eating cues from glands scattered throughout the body. [ILLUSTRATION OMITTED] Pituitary Gland pituitary gland, small oval endocrine gland that lies at the base of the brain. It is sometimes called the master gland of the body because all the other endocrine glands depend on its secretions for stimulation (see endocrine system). This pea-size "master gland mas·ter gland n. See pituitary gland. " secretes hormones that control most of the other endocrine glands endocrine glands (enˑ·dō·krin glandz′), n.pl ductless glands of the endocrine system that secrete hormones directly into the bloodstream. . [ILLUSTRATION OMITTED] Thyroid Secretes thyroxine, a hormone that speeds up the rate at which your body cells burn energy (metabolism). [ILLUSTRATION OMITTED] Did You Know? * Because of Americans' substantial weight increase in recent decades, airplanes are now carrying more weight than ever, according to a study by the Centers for Disease Control and Prevention. The increased heft causes more drag during flight, requiring the planes to use more fuel to fly. This factor contributes to increasing airfares. * In 2003, more than 25 percent of the adults in Alabama, Indiana, Mississippi, and West Virginia were considered obese. Resources * This Web site, created by the Centers for Disease Control and Prevention, helps students find fun ideas on how to stay active: www.verbnow.com/ * The Weight-control Information Network offers tips to adults on how to help overweight children: http://win.niddk.nih.gov/publications/over_child.htm
OVERSIZING PORTIONS
see for yourself
how an increase
in portion size
translates into a
jump in calories.
1955 2000
FRIES 2.3 oz 210 Calories 6.9 oz 610 Calories
SODA 6.5 oz 80 Calories 20 oz 250 Calories
CANDY BAR 1.1 oz 150 Calories 3.7 oz 510 Calories
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