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Overweight, Obesity and Weight Management

Backgrounder

Rates of overweight and obesity in the United States have grown to epidemic proportions over the last 20 years. In 2005, the Surgeon General estimated that two-thirds of Americans were overweight or obese. The latest data from the NCHS show that 30 percent of U.S. adults 20 years of age and older - more than 60 million people - are obese. The direct costs and indirect costs of overweight and obesity amounted to about $117 billion in 2000. Intangible costs (such as impaired quality of life) have not been estimated, but given the social and psychological consequences of obesity, they are likely to be enormous.

Childhood overweight and obesity rates are especially alarming. According to the National Center for Health Statistics (NCHS) report, Health, United States, 2005, 16 percent of children and adolescents aged six to 19 were overweight. The prevalence of overweight among children and adolescents has doubled and tripled, respectively, over a period of twenty-six years (1976-2002). Research shows that overweight children are more likely to become overweight adults and, therefore, are at greater risk for associated health problems. In fact, 60 percent of overweight five- to 10-year-old children already have at least one risk factor for heart disease.

While all children and adolescents are at risk, those belonging to certain ethnic population groups may be more predisposed to overweight than others. Data from the National Health and Nutrition Examination Survey (NHANES 2003-2004) indicated that the risk of overweight among Mexican-American children and adolescents aged two to 19 is 41 percent: more than five and 10 percentage points higher than their non-Hispanic white (35 percent) and non-Hispanic black (30 percent) contemporaries, respectively.

Global in Scope

Overweight and obesity are not just a U.S. issue; its prevalence is increasing throughout the world's population. The World Health Organization (WHO) reports that more than one billion adults are overweight and at least 300 million of them are clinically obese. Levels of obesity range from below five percent in China, Japan, and certain African nations to over 75 percent in urban Samoa.

Worldwide, over 22 million children under the age of five are overweight as are 155 million school-age children. In a 2006 review published in the International Journal of Pediatric Obesity, North America, Europe, and parts of the Western Pacific have the highest prevalence of overweight among children (approximately 20 to 30 percent). Furthermore, the levels of obesity among school-age children in countries undergoing economic growth, such as Brazil, Chile, Mexico, and Egypt, are catching up with fully industrialized countries. Based on the current secular trends and the International Obesity Task Force (IOTF) criteria, experts estimate that one in seven children in the Americas will be obese by 2010 as will one in every 10 children in the Eastern Mediterranean and European regions.

WHO considers obesity to be one of the top 10 causes of preventable death worldwide. While malnutrition and unsafe sex account for more deaths, high blood pressure, smoking, high cholesterol, and obesity are impacting both industrialized and developing countries. The 2003 Joint FAO/WHO Expert Consultation on Diet, Nutrition, and the Prevention of Chronic Diseases estimated that non-communicable diseases (NCDs) such as obesity, diabetes, hypertension, stroke, and various forms of cancer accounted for 60 percent of the 55.7 million deaths that occurred in 2000. If unchecked, NCDs are expected to contribute nearly 75 percent of all deaths by the year 2020.

Definitions and Measures of Overweight/Obesity

According to the National Institutes of Health (NIH), overweight refers to an excess of body weight compared to set standards. The excess weight may come from muscle, bone, fat, and/or bodily water. Obesity refers specifically to having an abnormally high proportion of body fat. A person can be overweight without being obese, as in the example of a bodybuilder or other athlete who has a lot of muscle. However, many people who are overweight are also obese.

The Centers for Disease Control and Prevention (CDC), researchers, and health professionals use Body Mass Index (BMI) as the preferred method for determining overweight and obesity in adults, though other methods exist and are in use. BMI is a calculation that divides a person's weight in kilograms by height in meters squared (BMI = [kg/m2]). BMI can also be calculated in pounds and inches: BMI = [lbs/in2] x 703. The general guideline currently recommended by the CDC is that individuals with a BMI of 25 to 29.9 are considered overweight, and those individuals with a BMI greater than 30 are considered obese. It is important to note that BMI does not use body fat or frame size in its calculations. Therefore, it is possible for an individual with a high proportion of lean body mass (muscle) to have an elevated BMI and not necessarily be at risk for adverse health conditions associated with overweight and obesity. These charts can be found at the CDC Web site: CDC Obesity.

For children, gender-specific BMI charts have been developed. Children with a BMI at or above the 95th percentile represented in these charts are considered overweight. Children in the 85th percentile are considered at risk for overweight. These charts can also be found on the CDC Web site: CDC BMI According to Age.

What are the Health Implications?

The consequences of overweight and obesity can range from psychological effects that impact quality of life (e.g. poor self-esteem, discrimination, depression) to physiological conditions that put an individual at risk for premature death. These conditions include the following:

  • Hypertension
  • Dyslipidemia (high total cholesterol or high levels of triglycerides)
  • Type 2 diabetes
  • Heart disease
  • Stroke
  • Gallbladder disease
  • Osteoarthritis
  • Sleep apnea and respiratory problems
  • Some cancers (such as endometrial, breast, and colon)

In research, the term "metabolic syndrome" has been widely used to refer to obesity, a combination of the above health factors - diabetes, hypertension, dyslipidemia - and signs of kidney disease. It has been suggested that the metabolic syndrome increases the risk for heart disease more than the individual health factors alone. However, a joint statement issued by the American Diabetes Association and the European Association for the Study of Diabetes asserts that there is no evidence supporting this theory. In other words, metabolic syndrome should not be treated as a unique cluster of diseases until the science behind it is clear.

Most health professionals believe that the more overweight an individual is, the higher the risk for developing health complications. Fortunately, the converse also appears true. By losing even 10 percent of body weight, an overweight individual can improve his or her health, providing the weight loss is maintained.

How Did We Get Here?

Prior to World War II, concern focused on health conditions caused by nutrient deficiency (e.g., hunger, rickets, beri beri). As the United States became more prosperous, attention began to shift from nutritional deficiencies to conditions associated with over-consumption (e.g., heart disease, elevated cholesterol, type 2 diabetes). However, in the 1970s, food insecurity was still the major focus in this country, behind the development of social and health programs. In the 1980s and 1990s, the focus was on nutrition and its impact on chronic disease; with specific attention to dietary fats. Only within the last decade have overweight and obesity been identified as important public health concerns.

Similar shifts toward over-consumption and sedentary lifestyles have occurred globally as other countries become increasingly westernized. Advancements in nutrition, hygiene, and the control of infectious disease are being replaced in developing countries by new health threats such as obesity, cardiovascular disease, and diabetes. As urbanization and incomes rise, traditional diets that are rich in complex carbohydrates and fiber are gradually replaced by western diets that are lower in these nutrients and high in calories. Thus, obesity often coexists with chronic under-nutrition in the same population, creating a double disease burden.

In the simplest of terms, weight gain occurs when calories consumed (from food and beverages) exceed calories expended (through basal metabolism, thermal effect of food, and physical activity). The rise in overweight and obesity can be attributed to an imbalance between calories consumed and calories expended or a shift away from healthful food and lifestyle choices. These have resulted from gradual changes in a complex set of social and environmental factors. Individuals have become less active in all areas of their lives. Work and free time have become much more sedentary. Food habits - such as diet composition, increased eating away from the home, and larger portion sizes - have also changed. There has also been a societal shift in the way communities are designed and built. Often, there is a lack of resources or foresight to design urban and suburban environments that encourage active lifestyles, such as sidewalks and walking paths. Areas that require more study are the impact of genetics and psychological factors on the development of overweight and obesity.

Strategies for Healthful Lifestyles and Weight Management

Eating Patterns and Physical Activity

The 2005 Dietary Guidelines for Americans provide sciencebased advice on healthful eating and physical activity for people over the age of two. MyPyramid - the new food guidance system released by United States Department of Agriculture (USDA) in 2005 - illustrates what and how much to eat from the basic food groups for health. It includes twelve food intake patterns that are consistent with the Dietary Guidelines and tailored to individual calorie needs based on age, gender, and physical activity level. More information can be found on the My Pyramid Web site: My Pyramid.

Only 49 percent of adults in the United States engage in regular physical activity consistent with recommendations, according to the latest Behavioral Risk Factor Surveillance System survey conducted by the CDC. Furthermore, many individuals who begin exercise programs either do not participate in them regularly or do not maintain them for the long-term. In addition, the development of new technologies and labor saving devices, changes in how we spend our leisure time, and transformations in community design all have contributed to an increase in sedentary behaviors in workplaces, schools, and at home. Physical activity does not have to be strenuous to maintain weight and promote health. MyPyramid, the American College of Sports Medicine, the CDC, and the Surgeon General recommend that individuals of all ages accumulate at least 30 minutes of moderate-intensity physical activity on most, preferably all, days of the week. To prevent weight gain, 60 minutes a day may be needed, based on the Dietary Guidelines and MyPyramid. Preliminary evidence shows that accumulated activity, or activity in short bursts, can provide health benefits, similar to sustained activity. Additional health benefits may be gained by increasing time or intensity of the activity and by including strength training. Short, intense bouts of activity can deliver similar benefits as longer, less intense sessions.

Promotion of Healthful Eating Guidelines and Messages

According to the 2002 Joint FAO/WHO Expert Consultation on Diet, Nutrition, and the Prevention of Chronic Diseases, mass media campaigns and other communication strategies, such as the former "Food Guide Pyramid" and the "5-A-Day for Better Health" campaign, can have significant impact on awareness, attitudes, knowledge, and intention to change. But behavior change is usually not influenced unless the message is highly specific and achievable.

This is consistent with the results of the IFIC Foundation's 2003 qualitative research, exploring consumers' perceptions n health and weight management. In a series of focus groups that tested six messaging concepts, a message that consumers particularly liked was, "Take a small step each day toward a healthy weight. Over time, small steps add up to big changes." In addition to being achievable, it was realistic and meaningful enough for them to cite several examples of "small steps" they can do to eat better and exercise more. Further details of this study may be found on the IFIC Foundation Web site: IFIC Research.

Treatment

Evidence-based reports - such as the 2000 National Institutes of Health (NIH) Practical Guide for Identification, Evaluation, and Treatment of Overweight and Obesity in Adults - summarize approaches to weight loss and maintenance. The general goals for weight loss and weight management are the following:

  1. Reduce body weight;
  2. Maintain a lower body weight over the long term; and,
  3. Prevent further weight gain as a minimum goal.

Weight loss should be achieved at a safe and healthful rate of 1-2 pounds per week based on a reduction of 500 to 1,000 calories per day. Six months is a reasonable time period to achieve a 10 percent reduction in body weight. Effective weight management requires multiple techniques and strategies including diet, physical activity, behavior therapy, pharmacotherapy, and weight loss surgery. Guidelines to selecting the appropriate treatments can be based on the degree of obesity as measured by BMI and the presence of comorbidities. Successful interventions for weight loss and maintenance may combine a low-calorie diet, increased physical activity, and behavior therapy. The addition of weight loss drugs may be useful in people who are not successful in losing the recommended one pound per week after six months. For people with clinically severe obesity (BMI >35 with comorbid conditions or a BMI >40) in whom other methods of treatment have failed, weight loss (or bariatric) surgery, is an option.

Bariatric surgery involves restricting the size of the stomach or bypassing a portion of the intestines which cause weight loss by limiting the amount of food a person can consume in one meal and decreasing the proportion of nutrients absorbed from a meal, respectively. A substantial number of complications are associated with the procedure, although most of these are minor. A recent review by the Agency for Healthcare Research and Quality, suggested that more studies are needed to confirm or refute the relative efficacy of bariatric surgery in less severe cases of obesity.

Summary

Rates of overweight and obesity have reached epidemic proportions in the United States and around the world. This epidemic creates increased health care costs associated with a variety of weight-related conditions such as heart disease, type 2 diabetes, hypertension, some cancers, and hundreds of thousands of premature deaths each year. The increase in childhood overweight is especially alarming because overweight children are more likely to become overweight or obese adults.

While several options to achieving weight loss and maintenance are available, prevention rather than treatment is the most desirable approach. Leading a healthful lifestyle by being physically active and practicing healthful eating habits can be enjoyed by people of all ages. A varied, moderate, and balanced diet combined with regular physical activity contribute to optimum health and well-being throughout one's life.

Source: Originally printed in the 2007-2009 IFIC Foundation Media Guide on Food Safety and Nutrition

Adapted by Editorial Staff, December 2007
Last update, August 2008

 


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