Restrained eating is associated with low leptin levels in underweight females

Psychometrically defined restrained eaters consume fewer calories, take fewer meals, show higher preference for low calorie foods, have lower energy expenditure and a higher rate of ovarial dysfunction than unrestrained eaters. We hypothesized that restrained eaters as assessed with the factor cognitive restraint of the Three-Factor Eating Questionnaire have low leptin levels; therefore, we measured serum leptin levels in 136 underweight students and 49 overweight students, who had filled out the Three-Factor Eating Questionnaire. Body mass indexes, fat mass and percent body fat were determined. Spearman correlations revealed that log10 leptin levels of only the 67 underweight females were negatively correlated with cognitive restraint scores (r = -0.5; nominal P-value < 0.001). The restraint score explained 22% of the total variance of leptin levels in underweight females; in combination with percent body fat, 52% of the variance was accounted for. To our knowledge this is the first study to identify a relationship between a score on a psychometric scale and leptin levels. Restrained eating has a biological correlate in underweight females.