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Keywords:

  • Obesity in Nursing;
  • obesity education;
  • nurses’;
  • knowledge of obesity

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Review of the literature
  5. Purpose and method
  6. Results
  7. Discussion
  8. Implications for research
  9. Acknowledgment
  10. References

Purpose: To quantify the incidence of overweight and obesity in nursing professionals and assess nurses’ knowledge of obesity and associated health risks.

Data sources: A mailed survey to 4980 randomly selected registered nurses from one state in each of six geographic regions. Response rate was 15.5% (n= 760). Descriptive statistics were calculated for continuous variables; categorical variables were summarized with frequency counts.

Results: The grand mean body mass index (BMI) of nurses surveyed was 27.2. Almost 54% were overweight or obese. Fifty-three percent of these nurses report that they are overweight but lack the motivation to make lifestyle changes. Forty percent are unable to lose weight despite healthy diet and exercise habits. Only 26% of respondents use BMI to make clinical judgments of overweight and obesity. Although 93% of nurses acknowledge that overweight and obesity are diagnoses requiring intervention, 76% do not pursue the topic with overweight and obese patients.

Discussion: Many nurses provide weight-related health information to the public. These data suggest that they may benefit from continuing education on obesity and its risks. Because 76% of nurses do not pursue the topic of obesity with patients, they may benefit from education on pursuing sensitive topics during a professional encounter. Nurse practitioners may play a key role in the education of both patients and registered nurses.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Review of the literature
  5. Purpose and method
  6. Results
  7. Discussion
  8. Implications for research
  9. Acknowledgment
  10. References

From bedside to advanced practice, and from administrator to academic scholar, all nurses share a particular commitment to health promotion and primary prevention. Nursing has always claimed patient education and wellness among its most important missions. As obesity becomes an alarming health problem nationwide, diet, exercise, and weight management become increasing priorities for all healthcare providers. Nursing should play an important role in the national effort to manage obesity and prevent obesity-related disease. Paradoxically, anecdotal observation suggests that nurses, advanced practice nurses, and nurse educators may exhibit a higher incidence of obesity than the general population. If this is true, it is important to learn why.

Several underlying issues may contribute to obesity in the nursing population. It could be that many practicing nurses do not truly understand the health implications of obesity. Alternatively, it could be that the diet and exercise strategies generally accepted as being effective in weight loss are just not practical for nurses on a daily basis. This study was conducted to make an assessment of both the incidence of obesity in the nursing population and the nurses’ knowledge of the health implications of obesity.

Review of the literature

  1. Top of page
  2. Abstract
  3. Introduction
  4. Review of the literature
  5. Purpose and method
  6. Results
  7. Discussion
  8. Implications for research
  9. Acknowledgment
  10. References

Overweight and obesity are widely recognized among the most common and devastating health problems in the United States. The problem is epidemic, affecting 100 million people nationally (U.S. Department of Health and Human Services, 2001). According to the most recent National Health and Nutrition Examination Survey (NHANES)—a national, cross-sectional survey of the noninstitutionalized population—nearly 51 million adults (31%) are obese (i.e., body mass index [BMI] ≥30). This survey also estimates that 65% of individuals aged 20 years and older in the United States are either overweight (BMI 25–30) or obese (BMI 30–40). Finally, an estimated 10 million people (4.7% of the population) are morbidly obese, defined as a BMI ≥40 or 200% of desired body weight (Centers for Disease Control and Prevention [CDC], National Center for Health Statistics, 2000; Gorroll & Mulley, 2000). The incidence of overweight and obesity increased by 300% over the past four decades (Dallal et al., 2003; Hill, Wyatt, Reed, & Peters, 2003). If the current trend continues, projecting NHANES data through 2008 suggests that the incidence of obesity in adults will rise to 39% with an additional 34% of adults being overweight (Hill et al.).

The health problems linked to overweight and obesity are numerous. Obesity is one of the single greatest risk factors for hypertension and heart disease, increasing the risk for each by a factor of five (National Heart, Lung, and Blood Institute, 2003). The link between obesity and diabetes mellitus type 2 is also well established (Uwaifo & Arioglu, 2004). Less well-known but equally significant risks of obesity include increased frequency and severity of degenerative joint disease, increased pulmonary disease, sleep apnea, and several cancers (Braunwald et al., 2005; Calle & Kaaks, 2004; Calle, Walker-Thurmond, & Thun, 2003; International Agency for Research on Cancer, 2002). For persons requiring surgery, obesity presents a significant risk in terms of poor or prolonged wound healing and general recovery (Way & Doherty, 2003). Overall, obese persons will experience a 12-fold increase in mortality when compared to persons of normal weight (Braunwald et al.). Of additional concern is the dramatic increase in overweight and obesity in childhood and adolescence. Current estimates show that 16% of U.S. children are overweight (American Obesity Association, 2002).

A variety of factors contribute to overweight and obesity, including metabolic or genetic abnormalities; however, the overwhelming majority of cases appear to be primarily linked to poor eating habits and sedentary lifestyle (American Obesity Association, 2002). Within the healthcare and lay communities, it is generally accepted that sound dietary management and regular physical activity are integral components of an effective weight loss and management program (Uwaifo & Arioglu, 2004). It is also generally accepted within the healthcare community that weight management is a multifaceted problem. The public frequently turns to nurses for both in-depth explanations, regarding why particular weight management interventions work, and assistance with the implementation of such interventions.

Nurses are a critically important resource for patients trying to understand and implement healthy behaviors. Because they interact with the community along all levels of the healthcare continuum, nurses can significantly influence patients trying to lose weight and maintain weight loss. One of nursing’s primary responsibilities is to provide both formal and informal patient education. Developing successful interventions for overweight and obesity, as well as motivating people to use them, is the subject of much investigation (Uwaifo & Arioglu, 2004). Strategies for motivating and implementing behavior changes remain elusive.

Nurses who clearly articulate both a rationale for healthy behaviors and a practical approach to implementing them are more likely to have greater success as patient educators. Role modeling healthy diet and lifestyle may positively impact patients. One questions whether healthcare consumers are more likely to embrace professional counseling when the nurse personally models those behaviors. Similarly, one must consider whether nursing students should be expected to respect and assimilate obesity management strategies when nurse educators do not appear to use those strategies. With respect to the professional nursing role, one may wonder if the obese nurse is an effective patient educator to the health risks of obesity. It may not be reasonable to expect healthcare consumers to be confident in a plan to reduce weight when the professional presenting that plan does not appear to model it.

Anecdotal observation of large groups of nurses suggests that obesity may be as prevalent among the profession as in the general population. This is a significant observation because this group of professionals is presumed to have an advanced knowledge of both the health-related risks of obesity and the methods for managing it. If these healthcare providers do not respond to obesity intervention, it may be unrealistic to expect the general public to do so. Potentially, nurses could reach millions of Americans with health education. If these informed professionals are not cognizant of obesity risks or responsive to interventions, it is a gap that should be thoroughly investigated.

Purpose and method

  1. Top of page
  2. Abstract
  3. Introduction
  4. Review of the literature
  5. Purpose and method
  6. Results
  7. Discussion
  8. Implications for research
  9. Acknowledgment
  10. References

Purpose

There were two purposes to this initial descriptive study. First, it provided a demographic assessment of nurses from representative states across the country. Gender, age, height, weight, level of physical activity, and other pertinent indices were collected. Second, it provided an assessment of nurses’ knowledge about obesity. Respondents answered questions regarding their knowledge level of overweight and obesity, including the definition of obesity, identification of obesity-related health risks, and the perception and importance of weight reduction. Other data, such as nursing specialty, shift work, and percentage of patient education hours, were collected to assess correlations among weight and work-related variables.

Methods

One state was selected at random from each of six geographic regions in the United States; the Northeast, East Coast, Midwest, South, Southwest, and Western U.S. mailing lists were purchased for all registered nurses in each of the six states. Microsoft Excel’s random numbers program randomized each list and randomly selected 860 names. After adjusting for incomplete addresses and other faulty mailing list data, a total of 4980 surveys were mailed (Table 1). Each name received a one-page letter of introduction and explanation, a two-page survey, and a stamped, self-addressed envelope. A total of 760 surveys were returned (see Table 2 for return by state). Because of limited funding, follow-up postcards were not sent. Institutional review board approval from the University of Nevada Las Vegas was obtained prior to mailing the surveys.

Table 1.  Respondents’ frequency by state
LocationFrequencyRelative frequency (%)
Alaska16521.7
Georgia688.9
Maine10213.4
Nebraska14418.9
New Mexico16421.6
West Virginia11515.1
Total760100.0
Table 2.  BMI by region
LocationMeanMedianSDRange
Alaska26.524.76.0617.5–48.7
Georgia27.725.87.0617.0–49.2
Maine27.426.55.8419.4–45.7
Nebraska25.924.56.1618.2–59.8
New Mexico27.025.16.5317.0–58.2
West Virginia29.528.27.7418.4–57.4

Statistical plan

Surveys received numbers for the order in which they were received; all data were entered into a spreadsheet for further analyses. Descriptive statistics were calculated when appropriate for continuous variables, and categorical variables were summarized with frequency counts. The log-likelihood (or likelihood ratio) statistic (G2) examined the potential association among categorical variables, namely: gender versus age, BMI versus age, educational attainment versus ability to identify health implications of obesity, and BMI versus feeling competent to provide obesity education to patients. This statistic is more robust than the commonly used chi-square statistic when expected frequencies are small (<5) and is essentially equivalent to the chi-square when expected frequencies are adequate (Zar, 1999). Therefore, we used this statistic throughout the Results section. Median BMI scores across regions were compared using a Kruskal–Wallis test (owing to nonnormality as assessed by the Shapiro–Wilk statistic), with multiple comparisons made using a Bonferonni-corrected p value. All analyses were conducted using SPSS (v. 14.0) and SAS (v. 9.1).

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Review of the literature
  5. Purpose and method
  6. Results
  7. Discussion
  8. Implications for research
  9. Acknowledgment
  10. References

Description of respondents

The 760 returned surveys represented all six states (Table 1). The mean BMI of respondents ranged from 25.9 to 29.5, indicating that all six states reported mean BMIs in the overweight range (Table 2). Ninety-two percent of respondents were female. Ages ranged from 22 to 85 years (M= 50.2, SD = 11.88, median = 51.0), with more than 50% between the ages of 45 and 64 years (Table 3). The observed and expected distribution of gender and age did not differ from that expected by chance (G2= 14.00, p= 0.374), nor did the observed and expected distribution of BMI and age differ from that expected by chance (G2= 86.91, p= 0.602). Ninety percent of the nurses were Caucasian, with the remaining 10% distributed among African American, Hispanic, Asian, and others (Table 4). Approximately 30% reported an associate’s degree as the highest academic degree earned, 42% a baccalaureate degree, 25% a master’s degree, and 2% a doctorate.

Table 3.  Age and BMI
Age (years)BMITotal by age category
<2020–24.925–29.930–34.935–39.940–44.945–49.9≥50
20–24081000009
25–2921570410029
30–34629145302160
35–39518133410044
40–444272110741074
45–4964335186140113
50–54651401811221131
55–5964742147732128
60–64627336840286
65–69516126200041
70–741982210023
75–79051100007
80–84001100002
85–89101000002
Total by BMI category48295229845421126749
Table 4.  Ethnicity and BMI
EthnicityBMITotal by ethnicity
<2020–24.925–29.930–34.935–39.940–44.945–49.9≥50
Caucasian44264208804820126682
African American0671300017
Hispanic11241110020
Asian1820000011
Other2662200018
Total by BMI category48296227845421126748

In terms of current practice role, approximately 72% of respondents described themselves as a registered nurse, 15% as an advanced practice nurse, and 5% as a nursing professor or instructor. The mean number of years in present role was 9.9; the mean number of years in nursing was 25.

Respondents, weight

The first purpose of this study was to compare the incidence of obesity in nursing to the general population. Of 760 total responses, 749 respondents provided height and weight information, allowing for a calculation of BMI. More than 30% of the respondents exhibited a BMI between 25 and 29.9. Tables 1 and 2 demonstrate that nurses as a population are overweight in each of the six states surveyed. Overall, the grand mean BMI of nurses surveyed was 27.2 (SD = 6.56, median = 25.6, range = 17–59.8). Thirty percent had an overweight BMI, 18.7% an obese BMI, and 5.2% a morbidly obese BMI (Tables 3 and 4). A total of 54.5% of the surveyed population is overweight, compared to 65% of the U.S. population (CDC, National Center for Health Statistics, 2000). Median BMI was not equal for all regions, F(5, 739) = 4.22, p < 0.001; West Virginia was significantly higher than Alaska (p= 0.006) and Nebraska (p < 0.001).

While the percentage of overweight and obesity is less than that of the general population, it is interesting that the average BMI of this health profession so heavily invested in health promotion and disease prevention is overweight. Of the 71% of respondents who specifically indicated that their professional role included health promotion education, 22% are obese (BMI >30) and 32% are overweight (BMI 25–29.9). Similarly, among nurses who report counseling patients specifically as to healthy diet practices, 21% are obese and 31% are overweight. Of 307 nurses who counsel patients in obesity prevention, 18% are themselves obese and 35% are overweight. Of 339 nurses who counsel patients in weight reduction, 18% are obese and 34% are overweight. Those who were obese were equally able to identify the negative health implications of obesity as were those of normal weight (G2= 5.73, p= 0.334).

One hundred seventy respondents (75%) identified themselves as overweight. Of 178 obese respondents, 173 acknowledged their obesity. Those respondents who identified themselves as overweight or obese were asked to choose from among the following three statements the one that best reflected their feelings about their weight.

  • A. 
    I recognize that I am technically overweight or obese, but I am comfortable and not interested in weight reduction.
  • B. 
    I lack the discipline to change diet/exercise habits, but I know I should.
  • C. 
    I eat a healthy diet and exercise regularly, but cannot lose excess weight.

Of 355 respondents who answered this question, 53% chose “B” and 40% chose “C.” The remaining 7% either chose “A” or some combination of the three responses.

Nurses’ knowledge of health implications of obesity

In accordance with the criteria of the International Obesity Task Force, overweight is clinically defined as a BMI >25 and obesity as a BMI >30 (Flegal, Carroll, Kuczmarski, & Johnson, 1998). Respondents were asked to describe how they differentiate overweight from obesity. Only 26% of the 758 nurses who answered this question indicated using BMI to make the distinction. Almost 20% of respondents used arbitrary weight distinctions to differentiate, including thresholds of 20, 50, and 100 lbs. For example, up to 20 lbs above ideal body weight would be overweight and anything more than 20 lbs would be obese. The remaining 54% reported several different subjective and objective mechanisms for distinguishing between the two (Table 5).

Table 5.  Differentiating overweight from obesity
ResponseFrequencyRelative frequency (%)
  1. ADL, activities of daily living.

Do not differentiate12716.8
Use BMI chart to differentiate between the two20226.6
Overweight = up to 20 lbs above ideal weight; obesity >20 lbs above ideal weight739.6
Overweight = up to 50 lbs above ideal weight; obesity >50 lbs above ideal weight496.5
Overweight = up to 100 lbs above ideal weight; obesity >100 lbs above ideal weight233.0
Obesity interferes with ADL; overweight does not necessarily interfere with ADL8611.3
Overweight is a certain percentage over ideal body weight; obesity is a greater percentage607.9
To differentiate is a subjective judgment152.0
Obesity is greater than being overweight486.3
Other759.9
Total758100.0

When asked to list at least three, but up to five unhealthy implications of obesity, results were surprising. Of 760 respondents, 4% failed to name one unhealthy implication of obesity and only 41% could name five (Table 6). Ninety-six percent of respondents identified cardiovascular disease as a consequence of obesity, which was expected. Otherwise, among all respondents and responses, 26% did not identify diabetes and 90% did not identify hypercholesterolemia. Other responses were distributed among joint pain and disease, pulmonary problems and sleep apnea, and other unidentified health problems (Table 7). Even though educational attainment may be speculated to be related to the ability to identify potential health implications, this was not the case. Indeed, the ability to name a particular health implication was independent of education level (G2= 16.54, p= 0.347).

Table 6.  Identifying unhealthy implications of obesity
Number of responses providedN (%)
032 (4)
12 (0.3)
28 (1)
3219 (29)
4188 (25)
5311 (41)
Table 7.  Unhealthy implications of obesity
Health implicationLevel of educationTotal number of responses
Associate’sBachelor’sMaster’sDoctorate
  1. DJD, degenerative joint disease; SOB, shortness of breath.

Diabetes16224413815559
Discrimination/decreased self-esteem85113807285
Joint problems/DJD871258312307
Cardiovascular problems/complications29040924627972
Cancer81720348
Increased cholesterol163519272
Interferes with active daily lifestyle/lack of exercise/poor diet110150846350
Pulmonary problems/SOB/sleep apnea5179423175
Body aches and pains17205042
Other health problems/medical conditions4957312139
Total by level of education21731017720724

Nurses’ approach to weight counseling

As reported, 71% of respondents indicated that health promotion education is a part of their professional role. While 93% of nurses acknowledge that overweight and obesity are diagnoses requiring intervention, 76% indicate that they do not pursue the topic even when they make the clinical judgment that the patient is overweight or obese.

Seven hundred and thirty-nine nurses responded to a question about their own competency to provide professional advice and counseling for patients interested in weight reduction. Overall, 51% indicated that they were competent; however, self-assessment of competency has no relationship to the respondents’ BMI. The overweight and obese respondents feel as competent as the normal BMI respondents to provide professional advice and counseling (G2= 3.54, p= 0.315). Sixty-two percent of respondents reported the need for continuing education regarding the health implications of overweight and obesity and 78% need continuing education regarding interventions.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Review of the literature
  5. Purpose and method
  6. Results
  7. Discussion
  8. Implications for research
  9. Acknowledgment
  10. References

The response rate of 15.5% was lower than anticipated, as 20% is the expected return rate for mail-survey research. Because of limited funding, reminder postcards were not sent. However, the data do support some interpretations that may be further investigated. For example, the incidence of overweight and obesity in the survey population was 54.5%, which is approximately 10% below the incidence in the general population. It is noteworthy that the mean BMI for all six reporting states was overweight, with West Virginia reporting a mean BMI in nurses that was just short of obesity at 29.5.

Because these are preliminary descriptive data, it is difficult to draw inferences with respect to cause; however, based upon responses to subsequent questions, some issues emerge. Of 224 overweight respondents, only 170 accurately identified themselves as overweight or obese. This suggests that some nurses do not understand the definitions of overweight and obesity.

When those who identified themselves as overweight or obese were asked to choose a statement that best characterized their feelings, over one half recognized that they lacked the discipline to change their lifestyle habits. A logical inference is that motivation, not knowledge, will be an important area of exploration for one half of the population who recognizes that they are overweight or obese.

Forty percent of those who recognize that they are overweight report that they eat a healthy diet and exercise regularly, but cannot lose weight. This perception is interesting as it is reported by a group of healthcare providers. While a small fraction of this group may have an underlying abnormality of physiologic metabolism, it is most likely that the large majority are either not appropriately characterizing a healthy diet and exercise pattern or not truly following one. Professional education will be very important for this group not only for their own health but because most nurses provide guidance and counseling to patients trying to manage overweight and obesity.

An assessment of nursing educational needs may be made from these data. As reported, only 26% of respondents identified BMI as the criteria by which they make weight-related diagnoses. Other respondents used a variety of subjective criteria not supported in the literature. Professional education initiatives for practicing nurses should begin with proper information about overweight and obesity classifications.

When asked to identify unhealthy implications of obesity, 96% of respondents identified cardiovascular disease. However, other results suggest a need for continuing education. Almost 26% did not identify diabetes and almost 90% did not identify hypercholesterolemia. Similarly, only 41% identified joint problems/degenerative joint disease and only 23% identified sleep apnea. Because primary and secondary prevention of disease is an important priority for national health care, recognition of obesity-related health risks is integral to the development of effective educational and motivational strategies. Health-related consequences of obesity will also be an important component of professional nursing education efforts.

Although 93% of nurses report that they acknowledge overweight and obesity as diagnoses requiring intervention, 76% indicate that they do not pursue the topic even when they make the clinical judgment that the patient is overweight or obese. This suggests that education regarding patient communication and initiation of potentially sensitive topics may be helpful. Skill and confidence in initiating a nonthreatening and nonjudgmental dialogue may prompt nurses to be proactive in taking advantage of this opportunity for primary and secondary prevention.

Finally, 62% of nurses report the need for continuing education regarding overweight and obesity health implications and 78% in the area of intervention. One half of nurses do not feel competent to provide professional weight-related counseling. These data suggest the opportunity to establish continuing nursing education programs to a receptive audience.

Implications for research

  1. Top of page
  2. Abstract
  3. Introduction
  4. Review of the literature
  5. Purpose and method
  6. Results
  7. Discussion
  8. Implications for research
  9. Acknowledgment
  10. References

Approximately one half of self-identified overweight and obese nurses identified a lack of discipline to make lifestyle changes. As stated previously, an important area of investigation will include identifying motivators for change. Identification of locus of control may also be instructive; locus of control could reasonably be the foundation from which successful motivators are identified. A more comprehensive descriptive assessment may also reveal other factors that contribute to lack of discipline. Conversely, 40% of self-identified overweight and obese nurses indicated that they do eat a healthy diet and exercise regularly. Therefore, an important area of investigation will evaluate how these nurses define a healthy diet and regular exercise.

Because the majority of nurses provide weight-related education to the public, both motivators and levels of weight-related education are important areas of investigation in this group of healthcare professionals. Ideally, they should be giving and role modeling accurate, evidence-based information. While successful management of the nation’s weight-related problems will include multiple contributions from a variety of disciplines, improving the tools with which nurses guide the public will be a worthwhile contribution to the overall national effort.

Acknowledgment

  1. Top of page
  2. Abstract
  3. Introduction
  4. Review of the literature
  5. Purpose and method
  6. Results
  7. Discussion
  8. Implications for research
  9. Acknowledgment
  10. References

This study was funded by an internal grant from the University of Nevada, Las Vegas.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Review of the literature
  5. Purpose and method
  6. Results
  7. Discussion
  8. Implications for research
  9. Acknowledgment
  10. References
  • American Obesity Association. (2002). Childhood obesity. Retrieved March 9, 2005, from http://www.obesity.org/subs/childhood/
  • Braunwald, E., Fauci, A. S., Hauser, S. L., Jameson, J. L., Kasper, D. L., & Longo, D. L. (2005). Harrison’s principles of internal medicine (16th ed.). New York: McGraw-Hill.
  • Calle, E. E., & Kaaks, R. (2004). Overweight, obesity, and cancer: Epidemiological evidence and proposed mechanisms. Nature Reviews, Cancer, 4, 579592.
  • Calle, E. E., Walker-Thurmond, K., & Thun, M. J. (2003). Overweight, obesity, and mortality from cancer n a prospectively studied cohort of U.S. adults. New England Journal of Medicine, 348, 16251638.
  • Centers for Disease Control and Prevention, National Center for Health Statistics. (2000). Prevalence of overweight and obesity in adults: 1999–2000. Retrieved June 27, 2006, from http://www.cdc.gov/nchs/products/pubs/pubd/hestats/obese/obse99.htm
  • Dallal, G. E., Das, S. K., Hsu, L. K., Kehayias, J. J., McCrory, M. A., Roberts, S. B., et al. (2003). Long-term changes in energy expenditure and body composition after massive weight loss induced by gastric bypass surgery. American Journal of Clinical Nutrition, 78, 2230.
  • Flegal, K., Carroll, M., Kuczmarski, R., & Johnson, C. (1998). Overweight and obesity in the United States: Prevalence and trends, 1960–1994. International Journal of Obesity and Related Metabolic Disorders, 22, 3947.
  • Gorroll, A. H., & Mulley, A. G., Jr. (2000). Primary care medicine: Office evaluation and management of the adult patient (4th ed.). Philadelphia: Lippincott Williams & Wilkins.
  • Hill, J. O., Wyatt, H. R., Reed, G. W., & Peters, J. C. (2003). Obesity and the environment: Where do we go from here? Science, 299, 853855.
  • International Agency for Research on Cancer. (2002). IARC handbooks of cancer prevention. Weight control and physical activity. France: Author.
  • National Heart, Lung, and Blood Institute. (2003). Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) Express (NIH Publication No. 5233). Bethesda, MD: National Institutes of Health.
  • U.S. Department of Health and Human Services. (2001). The Surgeon General’s call to action to decrease overweight and obesity. Retrieved March 9, 2006, from http://www.surgeongeneral.gov/library/
  • Uwaifo, G. I., & Arioglu, E. (2004). Obesity. Emedicine. Retrieved March 10, 2005, from http://www.emedicine.com/med/topic1653.htm
  • Way, L. W., & Doherty, G. M. (2003). Current surgical diagnosis and treatment (11th ed.). New York: Lange Medical Books/McGraw-Hill.
  • Zar, J. H. (1999). Biostatistical analysis (4th ed.). New York: Prentice-Hall.