Self-reported and measured height, weight, and BMI for 16,814 participants (8
,8,208 men and 8,606 women) were obtained according to calendar years. After adjusting for age and sex, the difference between self-reported and measured information did not significantly vary across calendar years for height (P
= .16), weight (P
= .31), or BMI (P
= .35). The percentage of participants who perceived their weight as about right remained constant (40% in 2001-2002, 39% in 2003-2004, and 39% in 2005-2006; P
= .92), despite an increase in measured BMI during these same time periods (27.2 kg/m2
, 27.9 kg/m2
, and 28.3 kg/m2
, respectively). Therefore, analyses are based on the combined years 2001 through 2006.
On average, men overreported their height by 1.22 cm (0.48 in) and their weight by 0.30 kg (0.66 lbs), and women overreported their height by 0.68 cm (0.27 in) and underreported their weight by −1.39 kg (−3.06 lbs) (). BMI was underestimated for both men and women.
Mean Difference Between Self-Reported and Measured Height, Weight, and Body Mass Index, by Sex, National Health and Nutrition Examination Survey, 2001-2006a
On average, both men and women significantly overreported their actual height, men more so than women (). Significant overreporting of height is greater among older men than younger men, among white and black non-Hispanic men than Hispanic men and men of other races/ethnicities, and among overweight and obese men than underweight or normal-weight men. Significant overreporting of height is greater among older women, Hispanic women, women in lower income categories, and overweight and obese women.
Mean Difference Between Self-Reported and Measured Height, Weight, and BMI in Men and Women, by Selected Characteristicsa
Self-reporting bias in weight significantly differs between men and women. Although men significantly overreport their weight in the age groups 16 to 39 years and 70 years or older, women significantly underreport their weight in the age range 16 to 79 years. Only white and black non-Hispanic men significantly overreport their weight, whereas all racial/ethnic groups for women significantly underreport their weight. Men in the income bracket $20,000 to $34,999 significantly overreport their weight, but women across all income categories significantly underreport their weight. Men in each BMI category significantly overreport their weight, with the exception of obese men, who significantly underreport their weight. Conversely, women who are normal weight, overweight, or obese significantly underreport their weight, increasingly so as BMI increases.
Self-reported height bias was significantly associated with age, sex, income, and BMI weight classification, but not with race/ethnicity. No significant interactions were found among these variables. Self-reported weight bias was also significantly associated with age, sex, income, and BMI weight classification, but not with race/ethnicity. Significant interactions were observed between age and sex (P = .01), age and income (P = .04), and age and BMI weight classification (P < .001). Significant overreporting of weight in men was found in the age groups 16 to 49 years and 70 years or older (). Conversely, women significantly underreported their weight in each age group. Underreporting of height is more pronounced in participants of higher income groups for people aged 50 to 69 years, but income has less of an influence on reporting bias in the younger or older age groups (data not shown). Underreporting of weight among people who are obese is significantly greater among people aged 16 to 49 years, followed by people aged 50 to 69 years, and then people aged 70 years or older.
Mean Difference Between Self-Reported and Measured Weight (kg), by Selected Variablesa
Approximately 39% (44% men and 34% women) thought their weight was about right, approximately 5% (7% men and 3% women) thought they were underweight, and 56% (48% men and 63% women) thought they were overweight. The difference in responses between men and women was significant (P < .001). The percentage who thought their weight was about right according to their actual BMI weight classification is presented in the Figure. Men were more likely than women to think their weight was about right if they were normal weight, overweight, or obese. Women were more likely than men to think their weight was about right if they were underweight.
Participants Who Perceived Their Weight as About Right, By Sex and BMI Classification, National Health and Nutrition Examination Survey, 2001-2006.
|Body Mass Index (kg/m2)||Sex|
|Male, % (95% CI)||Female, % (95% CI)|
|Underweight (<18.5)||32.0 (24.7-39.4)||57.7 (50.3-65.1)|
|Normal weight (18.5-24.9)||76.2 (74.0-78.4)||65.5 (63.2-67.7)|
|Overweight (25.0-29.9)||46.8 (44.1-49.5)||24.4 (22.3-26.5)|
|Obese (≥30.0)||12.0 (10.1-13.8)||4.9 (3.9-5.9)|