Perceived weight status, overweight diagnosis, and weight ... - Nature

9 downloads 0 Views 288KB Size Report
Nov 2, 2010 - 1Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, NC,. USA; 2Department of ...
International Journal of Obesity (2011) 35, 1063–1070 & 2011 Macmillan Publishers Limited All rights reserved 0307-0565/11 www.nature.com/ijo

ORIGINAL ARTICLE Perceived weight status, overweight diagnosis, and weight control among US adults: the NHANES 2003–2008 Study S Yaemsiri1, MM Slining2 and SK Agarwal1,3 1 Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, NC, USA; 2Department of Nutrition, Gillings School of Global Public Health and School of Medicine, University of North Carolina at Chapel Hill, NC, USA and 3Department of Medicine, University of Pittsburgh Medical Center, PA, USA

Objectives: To examine the association between perceived overweight status and weight control, discrepancies between perceived and measured weight status, and opportunities for health care professionals (HCPs) to correct weight perception among US adults. Design: Population-based cross-sectional study. Subjects: In all, 16 720 non-pregnant adults from the 2003 to 2008 National Health and Nutrition Examination Survey. Results: Overall, 64% (73% women, 55% men) reported a desire to weigh less and 48% (57% women, 40% men) reported pursuing weight control. Weight control was positively associated with overweight perception (odds ratio (OR) women 3.74; 95% confidence interval (CI) 2.96, 4.73; OR men 2.82; 95% CI 2.11, 3.76) and an HCP diagnosis of overweight/obesity (OR women 2.22; 95% CI 1.69, 2.91; OR men 2.14; 95% CI 1.58, 2.91), independent of measured weight status. A large proportion of overweight individuals (23% women, 48% men) perceived themselves as having the right weight. Also, 74% of overweight and 29% of obese individuals never had an HCP diagnosis of overweight/obesity. Although the majority of overweight/obese individuals (74% women, 60% men) pursued at least one weight management strategy, fewer (39% women, 32% men) pursued both dietary change and physical activity. Among overweight/obese adults, those with an HCP diagnosis of overweight/obesity were more likely to diet (74 versus 52%), exercise (44 versus 34%), or pursue both (41 versus 30%, all Po0.01) than those who remained undiagnosed. Conclusion: HCPs have unused opportunities to motivate their patients to control and possibly lose weight by correcting weight perceptions and offering counseling on healthy weight loss strategies. International Journal of Obesity (2011) 35, 1063–1070; doi:10.1038/ijo.2010.229; published online 2 November 2010 Keywords: perceived weight status; weight control; body image; NHANES; adults

Introduction Obesity increases risk of diabetes, coronary artery disease, stroke, cancer, premature death and contributes substantially to societal costs.1–3 As little as a 5% of weight reduction in overweight or obese individuals can decrease the risk of cardiovascular events.4 However, sustained weight loss has been difficult to achieve in clinical trials,5,6 and more so outside trial settings.7

Correspondence: Dr SK Agarwal, Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, 137 E. Franklin Street, Suite 32, Chapel Hill, NC 27514, USA. E-mail: [email protected] Received 18 May 2010; revised 22 September 2010; accepted 26 September 2010; published online 2 November 2010

Lack of motivation is an important barrier to successful weight loss and maintenance.2 Perceived weight status, rather than measured weight status, may be an important determinant of motivation to lose weight.8–12 However, little is known about how the discrepancy between perceived and measured weight status affects adoption of weight control behaviors. Health care professionals (HCPs) may increase the motivation of a patient by correcting weight perception and through supportive counseling.13,14 However, whether an HCP diagnosis of overweight/obesity influences the adoption of weight management strategies is not known. Also, the role of HCPs in correcting weight perception and influencing attitudes and behaviors toward weight loss is less studied. We used nationally representative data to examine the following: (1) the association between perceived overweight

Weight control among US adults S Yaemsiri et al

1064 status and weight control, (2) discrepancies between perceived and measured weight status and (3) opportunities for HCPs to correct weight perception among US adults.

Subjects and methods Study population We examined data from the National Health and Nutrition Examination Survey (NHANES), a nationally representative complex, multistage probability sample of the US civilian, non-institutionalized population conducted by the National Center for Health Statistics.15–17 To produce estimates with statistical reliability, we combined three 2-year cycles of the continuous NHANES 2003–2004, 2005–2006 and 2007–2008.18 Unless otherwise noted, survey questions and methods were consistent in all three waves. NHANES 2003–2008 oversampled lower income persons, adolescents 12–19 years, persons 60 þ years of age, African–Americans and Mexican–Americans.15–17 Beginning 2007, the entire Hispanic population was oversampled.17 Participants were interviewed in their homes and underwent a standardized physical examination in a mobile examination center. The survey protocol was approved by the National Centers for Health Statistics Ethics Review Board, and each participant provided written informed consent. Full details of the NHANES are available at http://www.cdc.gov/nchs/ nhanes.htm.

Response variables Trained interviewers questioned participants about their weight control using a computer-assisted personal interviewing system. The first outcome of interest was the dichotomous variable desire to weigh less. Participants were asked, ‘Would you like to weigh more, less, or stay about the same?’ We created a dichotomous variable to identify participants who desired to weigh less by combining participants who desired to weigh more or stay about the same. The second outcome of interest was the dichotomous variable pursuit of weight control, defined as either trying to lose weight or doing anything to keep from gaining weight during the past 12 months. Participants who were categorized as pursuing weight control and were further asked to report all of the ways they tried to lose weight or keep from gaining weight. We categorized these weight control strategies as (1) dietary changes, (2) physical activity or (3) other.

Explanatory variables We considered as covariates factors that could potentially influence weight management behavior: gender, race/ethnicity, age, measured body mass index (BMI) and waist circumference (WC) categories, perceived weight status and self-report of having a diagnosis of overweight/obese status, diabetes, hypercholesterolemia, myocardial infarction and International Journal of Obesity

hypertension by an HCP. During the physical examination, participant weight and height were measured using standardized procedures. BMI was calculated as measured weight in kilograms divided by measured height in meters squared, and classified as o18.5 kg m2 underweight, 18.5 to o25 kg m2 normal, 25 to o30 kg m2 overweight, X30 kg m2 obese.19 WC was categorized as high risk for men with measured WC 4102 cm and women with measured WC 488 cm and low risk otherwise.19 Participants were asked about their perceived weight status using the question, ‘Do you consider yourself now to be overweight, underweight, or about the right weight?’ Participants reported a diagnosis of overweight/obese status, diabetes, hypercholesterolemia, myocardial infarction or hypertension by an HCP.

Statistical analysis We limited the study sample to non-pregnant adults age 18 years or older. Pregnancy was determined either by participant report of pregnancy or a positive urine test. All analyses used appropriate weights for 6 years of data from 2003–2008 to account for the complex sampling design using SAS version 9.2 (SAS Institute Inc., Cary, NC, USA), unless otherwise noted. First, we examined the prevalence of overweight and obesity and the demographics of the study population. Next, we examined the prevalence of desire to weigh less and pursuit of weight control overall and by population subgroups. Results for men and women were reported separately to highlight possible differences in weight control attempts and perceived weight status. Prevalence estimates and standard errors were calculated using Proc Surveyfreq. We compared perceived body weight status (underweight, the right weight and overweight self-perception) with measured BMI and WC categories. The prevalence of individuals who have been diagnosed as overweight/obese was calculated in the sub-population of those who had reported seeing an HCP within the past 12 months. The associations between desire to weigh less, pursuit of weight control and perceived weight status were examined using multivariable logistic regression. In these models, which were stratified by sex, we simultaneously controlled for age, race/ethnicity, measured BMI category and HCP diagnosis of overweight/obesity, diabetes, high blood cholesterol, heart attack and high blood pressure. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using Proc Surveylogistic. Finally, we examined weight control practices in the subgroup of overweight or obese adults who reported having seen an HCP in the past year. Collection of weight control practices data were consistent only in the 2005–2006 and 2007–2008 waves of the survey. For this analysis only, we used appropriate weights for 4 years of data from 2005–2008 to account for the complex sampling design. The prevalences of dietary and physical activity weight

Weight control among US adults S Yaemsiri et al

1065 control strategies were reported overall and by HCP diagnosis of overweight/obese status. Sensitivity analyses were performed to evaluate whether the observed associations in the multivariable logistic models were sensitive to including education level and annual family income, or replacing BMI category with WC category (to avoid collinearity), but no substantial differences were found.

Results The study analysis included 16 720 non-pregnant adults age 18 years and older. All analyses used sampling weights to obtain prevalence estimates for US adults. About half (51%) were female and 30% were age 55 years or older. Approximately one-third of US adults were overweight (27.6% women, 39.4% men) and one-third were obese (34.1% women, 31.3% men). A large proportion of US adults, 64.3%, reported having a desire to lose weight. There was a higher prevalence of desire to lose weight among women than men (73.2% women, 55.1% men, Table 1). A desire to weigh less was reported by the majority of those who perceived themselves as overweight (98.3% women, 95.2% men) and those who received an HCP diagnosis of overweight/obesity (93.9% women, 91.4% men). The prevalence of desire to weigh less was higher among non-Hispanic whites than other racial/ethnic groups. Approximately one half (48.2%) of normal weight women desired to weigh less. Among men, the prevalence of desire to weigh less was higher in the all subgroups with an HCP diagnosis of a comorbidity than those without a diagnosis. However, among women, those with an HCP diagnosis of heart attack had a lower prevalence of desire to weigh less. Even though 64.3% of US adults desired to weigh less, a lower proportion reported pursuing weight control (48.4% overall, 57.1% women, 39.6% men, Table 2), and an even lower proportion reported trying to lose weight (37.0% overall, 46.2% women, 27.6% men). Similar to the gender pattern for desire to lose weight, a greater proportion of women reported pursuing weight control than men. Large proportions of US adults with an HCP diagnosis of overweight/obesity (75.1% women, 65.0% men) and those who perceived themselves as overweight (71.6% women, 59.6% men) pursued weight control. The prevalence of pursuit of weight control was greater among younger (o55 years) than older (X55 years) women, but was similar between older and younger men. Although prevalence of desire to weigh less increased with BMI category, the prevalence of pursuit of weight control did not increase as substantially among higher BMI categories. Less than half of men and women in the normal weight BMI category or low-risk WC category reported pursuing weigh control. Similarly, less than half of men with a diagnosis of high blood pressure, diabetes or heart attack pursued weight control.

Table 1 Prevalence of desire to weigh less among US adults, NHANES 2003–2008a Desired to weigh less, % (s.e.) Women (n ¼ 8281)

Men (n ¼ 8439)

Overall Age o55 Years (ref) X55 Years

73.2 (0.6)

55.1 (0.8)

74.9 (0.9) 69.5 (0.8)*

53.7 (1.0) 59.0 (1.2)*

Race/ethnicity Non-Hispanic White (ref) Non-Hispanic Black Mexican American Other Hispanic Other race, multiracial

74.6 71.4 73.1 68.4 61.5

(0.7) (1.6) (1.0) (3.4) (3.1)*

58.5 40.4 49.0 51.6 51.8

(0.9) (1.4)* (1.7)* (3.4)* (3.2)*

BMI category Underweight Normal weight (ref) Overweight Obese

2.3 48.2 84.4 95.9

(1.5)*,b (1.4) (1.0)* (0.4)*

0.1 11.6 60.3 89.8

(0.1)*,b (1.2) (1.1)* (0.9)*

WC category Low-risk (ref) High-risk

50.4 (1.3) 89.0 (0.5)*

32.8 (1.1) 85.8 (0.8)*

Perceived body weight Underweight Normal weight (ref) Overweight

7.5 (1.9)* 31.8 (1.2) 98.3 (0.2)*

2.8 (0.8)* 18.8 (0.9) 95.2 (0.4)*

HCP diagnosis versus no. diagnosis of c Overweight/obesity 93.9 (0.6)* High blood pressure 78.5 (0.8)* High blood cholesterol 79.4 (0.8)* Diabetes 78.6 (1.5)* Heart attack 68.2 (3.3)

91.4 68.1 70.7 68.2 59.6

(0.8)* (1.0)* (1.2)* (1.7)* (3.2)

Abbreviations: BMI, body mass index; HCP, health care professional; NHANES, National Health and Nutrition Examination Survey; ref, reference; WC, waist circumference. aEstimates are weighted row percents (s.e.). Data are from the NHANES, 2003–2008. Pregnant women and participants younger than 18 years old were excluded. bThe relative standard error (s.e. divided by the estimate) X0.30, indicating the sample size is too small, making the estimate potentially unreliable. cHCP diagnosis was based on self-report. *Pp0.05.

Discrepancies exist between measured and perceived weight category among overweight men and women (Table 3). Almost one half (48.1%) of overweight men perceived themselves as having the right weight. One in eight (13.0%) obese men perceived that they had the right weight and almost one in five (17.9%) normal weight men perceived themselves as underweight. Conversely, one quarter (23.4%) of normal weight women perceived themselves as overweight. The sex differences in the validity of perceived body weight decreased when using WC categories, rather than BMI categories for measured weight categories. Approximately one in six men and women with high-risk WCs incorrectly perceive themselves to have about the right weight. One-third (32.3%) of low-risk women and one-fourth of low-risk (25.5%) men perceive themselves to be overweight. International Journal of Obesity

Weight control among US adults S Yaemsiri et al

1066 Table 2 Prevalence of pursuit of weight control among US adults, NHANES 2003–2008a Pursuing weight control, % (s.e.) Women (n ¼ 8281)

Men (n ¼ 8439)

Overall Age o55 Years (ref) X55 Years

57.1 (0.8)

39.6 (1.0)

60.5 (0.9) 50.1 (1.3)*

39.2 (1.2) 40.7 (1.4)

Race/ethnicity Non-Hispanic White (ref) Non-Hispanic Black Mexican American Other Hispanic Other race, multiracial

58.8 54.0 54.5 50.7 50.3

(1.1) (2.0) (2.1) (3.9)* (3.6)*

41.5 33.1 31.7 42.7 38.9

(1.5) (1.2)* (1.8)* (3.2) (3.8)

BMI category Underweight Normal weight (ref) Overweight Obese

13.5 46.3 62.8 69.2

(3.2)* (1.3) (1.4)* (1.1)*

0.8 18.6 45.4 56.0

(0.7)*,b (1.3) (1.4)* (1.8)*

WC category Low risk (ref) High risk

48.4 (1.1) 64.7 (1.0)*

30.8 (1.3) 54.1 (1.5)*

Perceived body weight Underweight Normal weight (ref) Overweight

4.9 (1.7)* 37.3 (1.4) 71.6 (1.0)*

5.0 (1.3)* 25.2 (1.2) 59.6 (1.4)*

HCP diagnosis versus no. diagnosis of c Overweight/obesity High blood pressure High blood cholesterol Diabetes Heart attack

75.1 56.9 63.4 57.2 50.8

65.0 48.3 52.2 46.2 41.6

(1.3)* (1.2) (1.6)* (2.8) (4.4)

(2.3)* (1.6)* (1.5)* (2.9)* (3.1)

Abbreviations: BMI, body mass index; HCP, health care professional; NHANES, National Health and Nutrition Examination Survey; ref, reference; WC, waist circumference. aEstimates are weighted row percents (s.e.). Data are from the NHANES 2003–2008. Pregnant women and participants younger than 18 years old were excluded. bThe relative standard error (s.e. divided by the estimate) X0.30, indicating the sample size is too small, making the estimate potentially unreliable. cHCP diagnosis was based on self-report. *Pp0.05.

Overweight self-perception was the most important predictor of desire to weigh less and pursuit of weight control (Table 4). Women with overweight self-perception had 67 times higher odds (OR 66.85; 95% CI 46.69, 95.72) and men with overweight self-perception had 32 times higher odds (OR 32.41; 95% CI 22.62, 46.43) of desire to weigh less compared with those who perceived themselves as having the right weight. A positive association was observed between overweight self-perception and pursuit of weight control with an OR 3.74 (95% CI 2.96, 4.73) among women and an OR 2.82 (95% CI 2.11, 3.76) among men. Both desire to weigh less and pursuit of weight control were associated positively with an HCP diagnosis of overweight/obesity and high blood cholesterol independent of weight category in men and women. Increasing age was inversely associated with desire to weigh less and pursuit of weight control in both men and women. International Journal of Obesity

Interestingly, a large proportion of overweight/obese individuals were never diagnosed as overweight/obese by an HCP. Among individuals in the overweight BMI category, 69% of women and 78% of overweight men were never diagnosed as overweight/obese by an HCP (Table 3). Importantly, 27% of obese women and 31% of obese men remain undiagnosed as overweight/obese. Almost half of those in the high-risk WC category were never told they were overweight by an HCP. Although the majority of overweight or obese adults pursued at least one weight management activity (73.5% women, 60.3% men, Table 5), fewer pursued both diet and physical activity (38.6% women, 32.3% men). Overweight or obese individuals who were diagnosed as overweight/obese by an HCP had a higher prevalence of pursuing weight control than those without a diagnosis. Similarly, among overweight men and women, those diagnosed as overweight/obese by an HCP were more likely to diet, exercise or pursue both. However, about 18% of women and 26% of men made aware of their overweight status by an HCP did not use any weight control strategies.

Discussion In a recent nationally representative survey, three in five US adults desired to weigh less and one in two pursued weight control. We observed substantial discrepancies between measured and perceived weight status, particularly among males and those in the overweight BMI category. Overweight perception and HCP diagnosis of overweight/obesity were positively associated with desire to lose weight and pursuit of weight control, independent of measured weight status. Among overweight or obese individuals, those diagnosed as overweight/obese by an HCP were more likely to make dietary changes, exercise, or pursue both. However, the majority of overweight individuals were never made aware of their overweight status by an HCP. The prevalence of obesity increased from 22.9 to 30.5% between 1988 and 2000, but since then recent data suggests that the rate of increase has stabilized.20 The prevalence of pursuit of weight control follows the obesity trend through the mid-1990s. Using data from the Behavioral Risk Factor Surveillance System, the prevalence of attempted weight loss now was 40 and 23% in the 1989 and 44 and 29% in the 1996 among women and men, respectively.21 Serdula et al. attributed this increasing trend to the increasing prevalence of obesity in the population. The prevalence of trying to lose weight was 50 and 29% in NHANES III, 1998–1994,22 as compared with 46 and 28% in our report of NHANES 2003– 2008 for women and men, respectively. Although the prevalence of obesity continued to increase slightly over this time period, it seems the prevalence of desire to weigh less may have stabilized among men and decreased among women.

Weight control among US adults S Yaemsiri et al

1067 Table 3 Validity of perceived body weight status and diagnosis of overweight/obese status as compared with measured body mass index and waist circumference categories BMI categories

BMI

Diagnosed as overweight/obese, % (s.e.)a

Perceived body weight status, % (s.e.) Underweight

The right weight

Overweight

Women Normal weight Overweight Obese

18.5 to o25 25 to o30 X30

5.1 (0.4) 0.7 (0.2) 0.3 (0.1)

66.2 (1.2) 23.4 (1.1) 5.1 (0.5)

28.7 (1.2) 75.8 (1.2) 94.7 (0.5)

6.1 (1.0) 30.6 (1.4) 72.5 (1.7)

Men Normal weight Overweight Obese

18.5 to o25 25 to o30 X30

17.9 (1.2) 1.4 (0.2) 0.3 (0.1)

75.2 (1.4) 48.1 (1.3) 13.0 (1.0)

6.9 (0.8) 50.4 (1.3) 86.7 (1.0)

2.7 (0.5) 21.7 (1.5) 68.5 (1.3)

WC categories

WC

Women Low risk High risk

p88 cm 488 cm

7.3 (0.6) 0.5 (0.1)

60.4 (1.2) 15.0 (0.6)

32.3 (1.0) 84.5 (0.6)

8.2 (0.9) 54.0 (1.3)

Men Low risk High risk

p102 cm 4102 cm

11.0 (0.6) 0.4 (0.1)

63.5 (0.9) 18.3 (1.0)

25.5 (0.9) 81.3 (1.0)

9.9 (0.9) 58.9 (1.2)

Abbreviations: BMI, body mass index; WC, waist circumference. aDiagnosis of overweight/obese status by a health care professional was based on self-report and was only analyzed among participants who had reported receiving health care within the past 12 months. Table 4

Multivariable odds ratios for desire to weigh less and weight control

Characteristics

Multivariable odds ratios (95% confidence interval) Desire to weigh lessa

Age (per s.d.)c Race/ethnicity Non-Hispanic White Non-Hispanic Black Mexican American Other Hispanic BMI category Normal weight Overweight Obese Overweight self-perception HCP diagnosis of: Overweight/obesity High blood pressure High blood cholesterol Diabetes Heart attack

Pursuing weight controlb

Women

Men

Women

Men

0.53 (0.44, 0.64)

0.77 (0.65, 0.93)*

0.63 (0.54, 0.74)

0.74 (0.63, 0.87)

1 0.42 (0.27, 0.66) 0.59 (0.40, 0.86) 0.41 (0.23, 0.74)

1 0.38 (0.26, 0.57) 0.58 (0.36, 0.92) 0.60 (0.35, 1.04)

1 0.78 (0.58, 1.06) 0.78 (0.53, 1.14) 0.57 (0.36, 0.90)

1 0.89 (0.65, 1.21) 0.72 (0.52, 1.00) 1.17 (0.76, 1.81)*

1 2.29 (1.78, 2.95) 2.22 (1.28, 3.87)

1 4.98 (3.24, 7.63)* 7.32 (4.37, 12.26)*

1 1.03 (0.76, 1.39) 0.63 (0.45, 0.90)

1 1.39 (1.09, 1.78) 1.09 (0.79, 1.52)*

3.74 2.22 0.89 1.39 0.95 0.90

2.82 2.14 1.02 1.11 0.67 1.02

66.85 1.60 0.92 1.35 1.09 0.62

(46.69, 95.72) (0.97, 2.63) (0.61, 1.39) (0.99, 1.83) (0.56, 2.14) (0.34, 1.12)

32.41 2.45 0.99 1.42 0.68 0.59

(22.62, 46.43)* (1.56, 3.84) (0.71, 1.38) (1.11, 1.83) (0.40, 1.14) (0.31, 1.11)

(2.96, (1.69, (0.72, (1.12, (0.69, (0.46,

4.73) 2.91) 1.09) 1.72) 1.32) 1.77)

(2.11, (1.58, (0.79, (0.92, (0.51, (0.69,

3.76) 2.91) 1.31) 1.35) 0.87) 1.50)

Abbreviations: BMI, body mass index; HCP, health care professional. aReference category is desire to weigh about the same or more. bReference category is neither trying to lose nor maintain weight. cThe standard deviation (s.d.) of age was 20.04 years. *P-interaction p0.05 in a model that simultaneously included all interactions terms between the covariates and sex.

Increasing discrepancies in the perception of weight status may explain the diverging trends in trying to lose weight and obesity. Among overweight US adults, 11% of women and 33% of men in 1998–1994, and 23% of women and 48% of men in 2003–2008 believed they were about the right weight.23 These results suggest that that

misperceptions of weight status may be increasing. The high prevalence of overweight and obesity in the US may make the condition appear ‘normal’ as evident by an upward shift in desired weight among Americans.24–26 One study of weight perception in Great Britain also reported a marked decline in sensitivity in an individual’s overweight status.27 International Journal of Obesity

Weight control among US adults S Yaemsiri et al

1068 Table 5

Weight control practices in overweight or obese US adults, NHANES 2005–2008

Weight control practices, % (s.e)a

Overweight or obeseb

Women (n ¼ 4293) Any Diet Physical activity Physical activity and diet

73.5 69.2 41.4 38.6

(1.2) (1.2) (1.6) (1.4)

Overweight or obese womenb HCP diagnosisc

Men (n ¼ 4571) 60.3 55.3 36.6 32.3

(1.4) (1.4) (1.1) (1.0)

Yes (n ¼ 1710) 82.0 77.7 44.3 42.0

(0.9)* (1.1)* (1.8)* (1.6)*

No (n ¼ 1528) 63.3 59.1 37.9 34.4

(2.1) (2.0) (2.2) (1.9)

Overweight or obese menb HCP diagnosisc Yes (n ¼ 1279) 73.8 68.3 43.5 39.3

(1.8)* (2.0)* (1.3)* (1.4)*

No (n ¼ 1738) 49.9 45.2 31.4 26.9

(1.8) (1.7) (1.7) (1.4)

Abbreviations: HCP, health care professional; NHANES, National Health and Nutrition Examination Survey. aEstimates are weighted column percentages (s.e.). b Body mass index X25 kg m2, based on measured height and weight. cHeath care professional diagnosis of overweight/obesity only among those who have seen a doctor in the past year. *Pp0.05 for weight control practice among those with HCP diagnosis versus no HCP diagnosis.

That is, that fewer overweight and obese individuals identified themselves as overweight in 2007 than in 1999. Weight misperception occurred predominately among men. Gender differences in body image may explain this observation. On average, men tend to over-report their weight, expressing a desire to report a higher body mass.28 Among women, societal pressures, such as advertisement and mass media, and cultural norms may contribute to pushing misperception of body weight in the opposite direction as that of men. Of note, use of BMI categories as the ‘gold standard’ with which to compare weight perception may contribute to the idea that weight misperception occurs predominately among men.29 BMI standardizes body weight according to height, but does not distinguish between lean and fat tissues or provide information on body fat patterning. Individuals with high muscle mass, particularly men, may be misclassified as overweight using BMI categories.30 In contrast to BMI, WC has sex-specific cut points and is a measure of visceral adiposity. Both the gender differences and misperceptions were less pronounced in our examination of weight perception with respect to WC categories than with respect to BMI categories. Still, approximately one in six men and women with high-risk WC’s perceived themselves to have the right weight. Body weight dissatisfaction is associated with greater intentions to change weight, physical activity or diet.24 Incorrect perception of weight status is of concern, as our results support the mounting evidence that indicates overweight self-perception is an important predictor of pursuit of weight control.9,21,31 Positive associations between overweight self-perception and pursuit of weight control have been previously reported in studies with some limitations.8,11,32,33 Several were unable to examine the association independent of measured weight status. In the 1996 Behavioral Risk Factor Surveillance System, trying to lose weight was most strongly associated with self-reported BMI category (men: OR 7.56; 95% CI 7.01, 8.15; women: OR 5.18; 95% CI 6.60, 7.82), but investigators did not examine the association independent of measured weight status.21 Data from the 2004 Porter Novelli HealthStyles and ConsumerStyles survey supported the association between overweight self-perception and weight control.9 International Journal of Obesity

Overweight adults (categorized using self-reported BMI), who disagreed their body weight was a health risk had decreased odds of trying to lose weight (OR men 0.52; 95% CI 0.29, 0.93; OR women 0.45; 95% CI 0.24, 0.84). Although this report was unable to control for measured weight status, it did suggest that perceived weight status was an important predictor of trying to lose weight independent of selfreported BMI. The Aerobics Center Longitudinal Study was able to control for measured BMI. Investigators reported increased odds of intending to change physical condition and diet among men and women who had body dissatisfaction in all measured BMI categories.24 However, this study was conducted in a predominately white, middle-to-upper class cohort that may not be generalizable to the US population. Overall, these studies contribute to the growing literature on the positive association between overweight self-perception and pursuit of weight control and emphasize the need to correct weight perception. The positive association between having a diagnosis of high blood cholesterol and pursuit of weight control may be due to the clearly recommended lifestyle changes, including weight loss in overweight patients, for the treatment of high blood cholesterol.34 Opportunities to educate patients about weight maintenance in clinical settings remain insufficiently used.35 Despite an increasing prevalence of obesity, the proportion of obese individuals who received advice to lose weight decreased from 44% in 1994 to 40% in 2000.36 HCPs face many barriers to providing weight maintenance counseling, including a focus on treating acute illnesses rather than providing preventive care, lack of time and inadequate training. However, obese individuals may be seeking direct and specific information from HCPs about weight control.37 Among older populations and those with comorbidities, poor health or a lack of time or energy may contribute to making weight loss seem unachievable. HCPs can counsel patients that even modest weight reductions of 5–10% may improve blood pressure, serum lipid levels, glucose tolerance, and reduce incidence of diabetes and hypertension.4 A multidisciplinary team consisting of a primary-care physician, behavioral psychologist, registered dietitian and exercise psychologist may aid in the treatment of

Weight control among US adults S Yaemsiri et al

1069 obesity.38,39 Health professionals who wish to incorporate obesity counseling into their practice may find these references useful.35,40,41 National Heart, Lung and Blood Institute Clinical Guidelines recommend the combination of reduced calorie diet and increased physical activity to produce weight loss, decrease abdominal fat and increase cardio–respiratory fitness.19 Our analysis showed that 460% of overweight or obese adults pursued at least one weight management strategy, but o40% pursued both changes in diet and physical activity. Similarly, Bish et al. reported that among individuals trying to lose weight, fewer (13% women and 16% men) combined reduced calories with at least 200 min per week of physical activity.42 In addition to correcting weight perception, HCPs have an opportunity to educate overweight or obese patents about healthy weight loss strategies and normal weight patients about healthy weight maintenance strategies. Other weight loss strategies exist, such as bariatric surgery or use of prescription drugs, but were not examined in analysis as being a practical lifestyle change regardless of weight status. A major strength of our study is the use of a nationally representative sample rather than a sample of selected obese patients seeking medical care, which may not be generalizable to overweight individuals who are unaware of their weight status. In addition, use of standardized measurements of height, weight and WC provided reliable information about a participant’s measured weight status. The limitations of this study were primarily in self-report of diagnosis of health outcomes and pursuit of weight control. Self-reported diagnosis of overweight status may be subject to recall bias if those who perceive themselves to be overweight were more likely to report a diagnosis of overweight/obesity. It is possible that we overestimated the effect of overweight perception on pursuit of weight control if those in higher weight groups were also more likely to over report weight control attempts. The cross-sectional study design of the NHANES did not allow us to examine if overweight perception was associated with successful weight loss. Use of BMI as a measure of the high risk form of obesity may misclassify physically fit individuals with dense muscle mass as overweight. We addressed this limitation by additionally using WC as a measure of obesity. Finally, the majority of excess deaths due to overweight occur among individuals o70 years of age.1 Weight loss counseling should be approached with caution among those older than X70 years as this population may not benefit from weight loss or have special dietary needs and physical limitations that may prevent vigorous physical activity or make weight loss unhealthy.43,44 In conclusion, we report that overweight perception and HCP diagnosis of overweight/obesity were positively associated with weight control attempts in US adults. A diagnosis of overweight/obesity may correct weight perception and provide motivation to adopt healthy weight control practices.

Conflict of interest The authors declare no conflict of interest.

Acknowledgements We acknowledge the contributions made by NHANES participants and NHANES staff and investigators for making this data publicly available. We also acknowledge Thomas C Keyserling for his help reviewing a draft of the manuscript and Ruchika Goel Children’s Hospital, University of Pittsburgh Medical Center, for her help with framing the study question.

References 1 Flegal KM, Graubard BI, Williamson DF, Gail MH. Excess deaths associated with underweight, overweight, and obesity. JAMA 2005; 293: 1861–1867. 2 Haslam DW, James WP. Obesity. Lancet 2005; 366: 1197–1209. 3 Daviglus ML, Liu K, Yan LL, Pirzada A, Manheim L, Manning W et al. Relation of body mass index in young adulthood and middle age to medicare expenditures in older age. JAMA 2004; 292: 2743–2749. 4 Willett WC, Dietz WH, Colditz GA. Guidelines for healthy weight. N Engl J Med 1999; 341: 427–434. 5 Curioni CC, Lourenco PM. Long-term weight loss after diet and exercise: a systematic review. Int J Obes (Lond) 2005; 29: 1168–1174. 6 Franz MJ, VanWormer JJ, Crain AL, Boucher JL, Histon T, Caplan W et al. Weight-loss outcomes: a systematic review and meta-analysis of weight-loss clinical trials with a minimum 1-year follow-up. J Am Diet Assoc 2007; 107: 1755–1767. 7 Tsai AG, Wadden TA. Systematic review: an evaluation of major commercial weight loss programs in the United States. Ann Intern Med 2005; 142: 56–66. 8 Lemon SC, Rosal MC, Zapka J, Borg A, Andersen V. Contributions of weight perceptions to weight loss attempts: differences by body mass index and gender. Body Image 2009; 6: 90–96. 9 Gregory CO, Blanck HM, Gillespie C, Maynard LM, Serdula MK. Perceived health risk of excess body weight among overweight and obese men and women: differences by sex. Prev Med 2008; 47: 46–52. 10 Wardle J, Haase AM, Steptoe A. Body image and weight control in young adults: international comparisons in university students from 22 countries. Int J Obes (Lond) 2006; 30: 644–651. 11 Wardle J, Johnson F. Weight and dieting: examining levels of weight concern in British adults. Int J Obes Relat Metab Disord 2002; 26: 1144–1149. 12 Atlantis E, Barnes EH, Ball K. Weight status and perception barriers to healthy physical activity and diet behavior. Int J Obes (Lond) 2008; 32: 343–352. 13 Lewis BS, Lynch WD. The effect of physician advice on exercise behavior. Prev Med 1993; 22: 110–121. 14 Bull FC, Jamrozik K. Advice on exercise from a family physician can help sedentary patients to become active. Am J Prev Med 1998; 15: 85–94. 15 Centers for Disease Control and Prevention (CDC). National Center for Health Statistics (NCHS) National Health and Nutrition Examination Survey 2003–2004 Public Data General Release File Documentation. Available at http://www.cdc.gov/nchs/ data/nhanes/nhanes_03_04/general_data_release_doc_03-04.pdf.

International Journal of Obesity

Weight control among US adults S Yaemsiri et al

1070 16

17

18

19

20

21

22

23 24

25

26

27

US Department of Health and Human Services, Centers for Disease Control and Prevention: Hyattsville, MD. Centers for Disease Control and Prevention (CDC). National Center for Health Statistics (NCHS) National Health and Nutrition Examination Survey 2005–2006 Public Data General Release File Documentation. Available at http://www.cdc.gov/nchs/data/ nhanes/nhanes_05_06/general_data_release_doc_05_06.pdf. US Department of Health and Human Services, Centers for Disease Control and Prevention: Hyattsville, MD. Centers for Disease Control and Prevention (CDC). National Center for Health Statistics (NCHS) National Health and Nutrition Examination Survey 2007–2008 Public Data General Release File Documentation. Available at http://www.cdc.gov/nchs/nhanes/ nhanes2007–2008/generaldoc_e.htm US Department of Health and Human Services, Centers for Disease Control and Prevention: Hyattsville, MD. Centers for Disease Control and Prevention (CDC). National Center for Health Statistics (NCHS) National Health and Nutrition Examination Survey Analytic and Reporting Guidelines. Available at http://www.cdc.gov/nchs/data/nhanes/nhanes_03_ 04/nhanes_analytic_guidelines_dec_2005.pdf. US Department of Health and Human Services, Centers for Disease Control and Prevention: Hyattsville, MD. National Institutes of Health, National Heart, Lung, and Blood Institute. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. National Institutes of Health, National Heart, Lung, and Blood Institute: Bethesda, MD, 1998. Flegal KM, Carroll MD, Ogden CL, Johnson CL. Prevalence and trends in obesity among US adults, 1999–2000. JAMA 2002; 288: 1723–1727. Serdula MK, Mokdad AH, Williamson DF, Galuska DA, Mendlein JM, Heath GW. Prevalence of attempting weight loss and strategies for controlling weight. JAMA 1999; 282: 1353–1358. Villanueva EV. The validity of self-reported weight in US adults: a population based cross-sectional study. BMC Public Health 2001; 1: 11. Chang VW, Christakis NA. Self-perception of weight appropriateness in the United States. Am J Prev Med 2003; 24: 332–339. Kuk JL, Ardern CI, Church TS, Hebert JR, Sui X, Blair SN. Ideal weight and weight satisfaction: association with health practices. Am J Epidemiol 2009; 170: 456–463. Maynard LM, Serdula MK, Galuska DA, Gillespie C, Mokdad AH. Secular trends in desired weight of adults. Int J Obes (Lond) 2006; 30: 1375–1381. Johnson-Taylor WL, Fisher RA, Hubbard VS, Starke-Reed P, Eggers PS. The change in weight perception of weight status among the overweight: comparison of III NHANES (1988–1994) and 1999–2004 NHANES. Int J Behav Nutr Phys Act 2008; 5: 9. Johnson F, Cooke L, Croker H, Wardle J. Changing perceptions of weight in Great Britain: comparison of two population surveys. BMJ 2008; 337: a494.

International Journal of Obesity

28 Merrill RM, Richardson JS. Validity of self-reported height, weight, and body mass index: findings from the National Health and Nutrition Examination Survey, 2001–2006. Prev Chronic Dis 2009; 6: A121. 29 Kuchler F, Variyam JN. Mistakes were made: misperception as a barrier to reducing overweight. Int J Obes Relat Metab Disord 2003; 27: 856–861. 30 Rothman KJ. BMI-related errors in the measurement of obesity. Int J Obes (Lond) 2008; 32 (Suppl 3): S56–S59. 31 Wharton CM, Adams T, Hampl JS. Weight loss practices and body weight perceptions among US college students. J Am Coll Health 2008; 56: 579–584. 32 Anderson LA, Eyler AA, Galuska DA, Brown DR, Brownson RC. Relationship of satisfaction with body size and trying to lose weight in a national survey of overweight and obese women aged 40 and older, United States. Prev Med 2002; 35: 390–396. 33 Wee CC, Davis RB, Phillips RS. Stage of readiness to control weight and adopt weight control behaviors in primary care. J Gen Intern Med 2005; 20: 410–415. 34 National Cholesterol Education Program (NCEP) Expert Panel. Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) final report. Circulation 2002; 106: 3143–3421. 35 Manson JE, Skerrett PJ, Greenland P, VanItallie TB. The escalating pandemics of obesity and sedentary lifestyle. A call to action for clinicians. Arch Intern Med 2004; 164: 249–258. 36 Jackson JE, Doescher MP, Saver BG, Hart LG. Trends in professional advice to lose weight among obese adults, 1994 to 2000. J Gen Intern Med 2005; 20: 814–818. 37 Potter MB, Vu JD, Croughan-Minihane M. Weight management: what patients want from their primary care physicians. J Fam Pract 2001; 50: 513–518. 38 Grumbach K, Bodenheimer T. Can health care teams improve primary care practice? JAMA 2004; 291: 1246–1251. 39 Funnell MM, Brown TL, Childs BP, Haas LB, Hosey GM, Jensen B et al. National standards for diabetes self-management education. Diabetes Care 2009; 32 Suppl 1: S87–S94. 40 Whitlock EP, Orleans CT, Pender N, Allan J. Evaluating primary care behavioral counseling interventions: an evidence-based approach. Am J Prev Med 2002; 22: 267–284. 41 Rippe JM, McInnis KJ, Melanson KJ. Physician involvement in the management of obesity as a primary medical condition. Obes Res 2001; 9 (Suppl 4): 302S–311S. 42 Bish CL, Blanck HM, Serdula MK, Marcus M, Kohl III HW, Khan LK. Diet and physical activity behaviors among Americans trying to lose weight: 2000 behavioral risk factor surveillance system. Obes Res 2005; 13: 596–607. 43 Allison M, Keller C. Physical activity in the elderly: benefits and intervention strategies. Nurse Pract 1997; 22: 53–54 56, 58 passim. 44 Miller SL, Wolfe RR. The danger of weight loss in the elderly. J Nutr Health Aging 2008; 12: 487–491.