Obesity is defined as an excess accumulation of body fat. This excess accumulation is the result of a positive energy balance where caloric intake exceeds caloric expenditure. Recent evidence suggests that American adult men and women today consume, respectively, 116 and 112 more calories per day than in the mid 1970′s. 
In a study of temporal trends in energy intake in the United States between 1970 and 1998, Harnack et al. concluded that consistent with trends in overweight, most ecologic data suggests that energy intake has increased and is a likely contributor to the observed increases in average bodyweight.  Since the caloric value of fat is known (~3,500 calories), this translates into a potential weight gain of one pound approximately every 31 days or 11–12 lbs per year. Obviously, the “fattening of America” hasn’t occurred at this astounding rate, suggesting that energy outputs are also slightly greater due to larger body mass or an increase in physical activity and thus energy expenditure. Since physical activity rates over the past three decades are essentially unchanged or lower, it would seem that increased body mass has limited the weight gain due to increased energy output. 
Thus, overweight and obesity have increased dramatically, particularly since the 1980′s, throughout the world. This trend prompted the World Health Organization (WHO) in 1998 to recognize a “global epidemic of obesity.” 
In 1998, the National Institutes of Health (NIH) published guidelines for the identification, evaluation, and treatment of overweight and obesity in adults.  Body mass index (BMI), expressed as a weight/height ratio (kg/m 2 ), is recommended to distinguish between overweight (BMI is between 25 and 29.9) and obesity (BMI greater than or equal to 30). Obesity is further subdivided into three categories based on increasing disease risk as described below. 
Three classes of obesity Obesity Class BMI (kg / m)
It also is important to consider the distribution of body fat. Excess body fat in the abdomen is an independent predictor of the presence of risk factors such as diabetes mellitus (DM), high blood pressure, and abnormal blood lipids.  The NIH document recognized that, particularly in men and women with BMI’s between 25–34.9, a waist circumference of > 40 and > 35 inches in men and women, respectively, further increases the risk of morbidity and mortality. Finally, studies support the importance of considering percentage of body fat or the ratio of fat to lean body mass, particularly in relationship to risk of obesity-related diseases. 
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According to the Centers for Disease Control and Prevention (CDC) Behavioral Risk Factor Surveillance System (BRFSS), self-reported prevalence of obesity among US adults increased from 12% in 1991 to 18% in 1998.  Data from the 1988 to 1994 National Health and Nutrition Examination Survey (NHANES) suggested that 63% of men and 55% of women were overweight.  More recent (1999) data from NHANES IV found that obesity rates among adult Americans increased from 15% in 1980 to 27% in 1999. 
America regrettably is a world leader in the epidemic of overweight and obesity, but it does not stand alone. Surveys in Europe and the Far East show that over the last 10-20 years, rates of overweight and obesity have increased by 1.5 to 2.0 fold in many countries.  Recent reports from Hong Kong and the Republic of China suggest an emerging epidemic of obesity which is directly related to the increasing dietary fat and calories.
The magnitude of the increased prevalence of obesity in the US between 1991 and 1998 varies by region. It ranges from 31.9% in the mid-Atlantic to 67.2% in the south Atlantic regions.  The increased prevalence also varies considerably by state ranging from 11.3% in Delaware to 101.8% for Georgia.  In another survey, Missouri ranked 2nd in overweight.  The magnitude of the increase is greatest in 18 to 29 year olds (7.1% to 12.1%), those with some college education (10.6% to 17.8%), and those of Hispanic ethnicity (11.6% to 20.8%). 
Although attempts to lose weight are common in the United States (36.2% of the population in the 1998 BRFSS were trying to lose weight), the prevalence of overweight and obesity continues to increase.  An additional 55.6% of respondents in the 1998 BRFSS indicated they were trying to maintain their current bodyweight. One third of the respondents indicated they were consuming fewer calories and fat, and 60% indicated they were using exercise to assist with weight control. However, other studies indicate that most persons attempting to lose weight through exercise and diet are neither doing enough exercise nor are they using sound dietary principles. 
The annual economic costs of obesity are estimated to be > 70 billion dollars.  In spite of the health and economic burden of obesity, studies show that health professionals do not consistently advise overweight and obese patients that they should lose weight.   In fact, the 200 BRFSS revealed that only 14.5% of patients were counseled about weight whether it was to lose, gain, or maintain bodyweight. 
Thus, there is clearly a global epidemic of overweight and obesity. It can be estimated that, at the present rate of increasing prevalence of obesity, by the year 2030, 90% of US adults will be obese! We think it’s time to seriously address this issue and establish a nationwide campaign to help American adults achieve and maintain healthy body weights.
Health Risks of Obesity
Overweight and obesity are risk factors for numerous chronic diseases. After statistically accounting for tobacco use, an estimated 325,000 deaths each year are attributable to obesity (body mass index [BMI] > 30.0).  Several studies confirm a strong relationship between BMI and mortality in US adult men and women.    
Calle et al. reported that the lowest risk for mortality in a 14 year follow-up of a large cohort of 457,785 men and 588,369 women was at a BMI of 23.5 to 24.9 in men and 22.0 to 23.4 in women.  The relative risk for mortality in the heaviest BMI group ( > 40) was 2.58 in men and 2.0 for women compared to those in the group between 23.5 and 24.9 in men and 22.0 and 23.4 in women. A high body mass index was most predictive of death from coronary vascular disease (CVD), especially in men (relative risk = 2.90). The CVD risk of overweight and obesity was greater in Caucasians than African-Americans.
Similar findings in large cohorts were reported previously by Manson et al. (women) and Stevens et al. (men and women) although the nadir of their curves was somewhat lower at between 19 and 22 BMI.   In the study by Manson et al., the lowest mortality over 16 years was observed among women who weighed at least 15% less than the U.S. average for women of similar age and among those whose weight had remained stable since early adulthood. 
In a 26-year study of 26,000 white Seventh Day Adventist women who never smoked and were healthy at baseline, the relative risk of death was lowest for 30-54 year old women at a BMI between 21.3 to 22.9.   For women between 55 and 74 years of age, the lowest relative risk was found at a BMI between 23.0 to 24.8.
A recent ten-year follow-up report of middle aged women (Harvard Nurses’ Health Study) and men (Health Professionals Follow-up Study) looked at the impact of overweight on the risk of developing common chronic diseases during a 10-year period.  The most significant and startling finding from this study was that men and women with a BMI over 35 were approximately 20 times more likely to develop diabetes mellitus (DM) than their same-sex peers with a BMI between 18.5 and 24.9. Additionally, women and men who were not obese, but were overweight (BMI’s between 25 and 29.9) were at 1.5 to 2.0 fold greater risk of developing gallstones, hypertension, high cholesterol, colon cancer, heart disease, or stroke. The results of another study also found that persons with coronary artery disease (CAD) and a BMI greater than 35 had a seven-fold increased risk for mortality compared to persons with CAD and a BMI less than 25. 
Chronic diseases are the leading causes of mortality and morbidity in the United States and they pose a tremendous public health challenge. Clearly, one of the most well-established risk factors for chronic diseases is overweight and obesity. In fact, a recent report from the RAND Corporation found that after controlling for demographics, obesity was associated with more chronic conditions and worse physical health-related quality of life than tobacco use or poverty. 
Health Benefits of Intentional Weight Loss
Prospective epidemiological studies have shown that weight loss, weight gain, and weight cycling (frequent episodes of weight loss and regain) are all related to increased mortality compared with a stable weight.  Since unintentional weight loss is often associated with symptomatic disease, it is apparent why mortality might be increased. Weight gain clearly increases the prevalence of several risk factors for chronic disease and, thereby, would be expected to increase morbidity and mortality. Recent studies also have demonstrated that weight cycling is associated with increased health risks.    Many epidemiological studies of weight loss have not adequately addressed these issues creating confusion among the public. It is the author’s perspective that the evidence regarding sustained weight loss in adulthood clearly supports the health benefits of intentional weight loss and maintenance.
Numerous studies show that weight loss, even if only 5-10%, significantly improves lipoproteins,   hypertension,  DM and insulin resistance,  risk for osteoarthritis and it’s symptoms,  risk for selected cancers,  and other risk factors for chronic diseases. 
A recent study from Finland of nearly 500 men and women at risk for type 2 DM who were randomized to intensive lifestyle modifications or standard care found a 58% reduction in new cases of DM over three years.  None of the subjects who achieved all five study goals (weight loss of 5-10%, 30-45 minutes of physical activity, 4-5 days per week, < 30% fat calorie intake, < 10% saturated fat calorie intake, and 15 grams of fiber per 1000 calories) developed DM. This study was a multifactorial design, but included common lifestyle changes (i.e., increased physical activity and a 30% or less fat diet with increased fiber) aimed at weight loss. Clearly even small amounts of weight loss can significantly improve risk factors for CVD and other chronic diseases. However, it is not clear whether the benefits of moderate weight loss are sustained long term. One basic problem has been the inability to successfully maintain significant long-term weight loss. The Finnish study which was the first published randomized clinical trial of diabetes prevention through lifestyle changes suggests that sustained modest weight losses of 5% of bodyweight can indeed reduce the risk of developing a chronic disease. 
Several recent large prospective studies suggest that intentional weight loss is associated with decreased mortality.    One study of 43,457 women found that any amount of intentional weight loss resulted in health benefits.  In this study, women who intentionally lost weight had a 40-50% decrease in deaths from obesity-related cancers and a 30-40% decrease in death from type 2 DM. Another study of 49,337 men reported a 32-36% decline in death from DM among men with health problems who intentionally lost weight. 
It is beyond the scope of this case to thoroughly review and discuss the benefits of intentional weight loss. However, it seems clear that numerous health benefits are potentially derived from weight loss, particularly when it is intentional and sustained over the long term. Throughout the management plan for the case study presented in this paper, additional evidence will be provided for the health benefits associated with intentional weight loss.