[Discordance between nutritional status and self perception of weight among adults from Talca, Chile]

Obesity is related to underestimation of one's own weight.

To determine the agreement between nutritional status and self perception of weight status in apparently healthy adults from Talca.

Data were obtained from a survey applied at 1007 randomly selected subjects, aged 18-74 years old (66% women). The survey identified age, gender, educational level and socioeconomic status. Self-perception of weight was estimated with pictures representing the four nutritional status categories: underweight, normal, overweight and obese. Body Mass index (BMI, kg/m(2)) was calculated to determine nutritional status. Statistical analysis included kappa index, Bowman s symmetry test and a logistic regression model to calculate the odds ratio in different variables related to underestimation of weight.

Seventy three percent of subjects were overweight or obese and 44% underestimated their nutritional status. Sixty percent of subjects with a BMI between 25 and 26 kg/m(2), perceived themselves as normal. A higher underestimation was observed in obese subjects (odds ratio (OR) 17.2 95% confidence intervals (CI) 10.9-27.1), in overweight individuals (OR 3.5 95% CI 2.3-5.3), in men (OR 1.5 95% CI 1.1-2.1) and in people aged from 45 to 59 years (OR 1.7 95% CI 1.0-2.7).

Almost half of studied population had an erroneous self-perception of weight, mainly due to underestimation. Obese subjects, males and people older than 45 years were those with the higher degree of underestimation.