Validity of self-reported height, weight, and body mass index: findings from the National Health and Nutrition Examination Survey, 2001-2006.

Our study extends previous studies that have evaluated the level of bias in self-reported height and weight and corresponding body mass index (BMI). Results are evaluated by age, sex, income, race/ethnicity, and BMI classifications. Analyses are based on the National Health and Nutrition Examination Survey (NHANES) from 2001-2006. The sample was 8,208 men and 8,606 women aged 16 years or older. On average, men overreport their height by 1.22 cm (0.48 in) and their weight by 0.30 kg (0.66 lbs), and women overreport their height by 0.68 cm (0.27 in) and underreport their weight by -1.39 kg (-3.06 lbs). Overreporting of height significantly increases with age after age 50 for men and after age 60 for women. Overreporting of weight in men is significant in the age groups 16 to 49 years and 70 years or older. Women significantly underreport their weight in each age group but more so in the age group 16 to 49 years, followed by 50 to 69 years, and then 70 years or older. Men are more likely than women to think their weight is about right if they are at a normal weight or are overweight or obese, but women are more likely to think their weight is about right if they are underweight. Men and women significantly overreport their height, increasingly so at older ages. Men tend to overestimate their weight, but women underreport their weight, more so in younger ages. Corresponding BMI is underestimated, more so for women than for men at each age and increasingly so with older age for both sexes.