Decoding unintentional weight loss: How the right questions make a difference

Malnutrition screening tools often include questions about unintentional weight loss (UWL). It is unclear whether individuals who intentionally desire to lose weight or perceive themselves as overweight interpret questions regarding UWL accurately. We assessed potential misclassification of UWL-related questions in these groups.

Data from the Lifelines cohort was used (ñ125.000, age >18 years). Prevalence ratios (PRs) were calculated with a simple question regarding UWL as the dependent variable and the desire to lose weight and perception of one's body weight (too heavy vs. just right/too light) as separate independent variables. Associations were stratified by body mass index (BMI) group (normal weight vs. overweight/obesity) and adjusted for various comorbidities, demographics, and quality of life.

Of participants with normal weight, 30.3 % desired to lose weight, 37.9 % perceived their body weight as too heavy and 5.1 % reported UWL; this was 80.1 %, 92.7 % and 2.7 % for those with overweight/obesity. In both BMI groups, the prevalence of UWL was ∼60 % lower in participants who desired to lose weight or perceived themselves as too heavy (prevalence ratios 0.40-0.43, p-value <0.05).

Since there is no logical basis for the desire to lose weight or one's perception of body weight to prevent UWL, lower reported prevalence rates on UWL-related questions are likely the result of misinterpretation. Malnutrition screening tools that include questions regarding UWL might underestimate the prevalence rates of malnutrition in higher BMIs, as individuals in these groups often aspire to lose weight or perceive themselves as too heavy.