Introduction Dropout is a highly prevalent and serious problem in assessing the effectiveness of weight loss studies and a major cause of treatment failure in the management of morbidly obese patients. Objectives To determine which tests used for the psychometric evaluation of morbidly obese patients are more predictive of success/dropout in a weight loss program. Methods Sixty patients aged 18–65 attending the Outpatient Obesity Clinic between 2009 and 2011, were recruited for an intensive life style weight loss program. We compared the results obtained in Hamilton Depression scale, Hamilton Anxiety scale, Golombok Rust Inventory of Sexual Satisfaction, Eating Disorders Inventory-2, SF-36 Health Survey and Plutchik's Impulsivity questionnaire between patients who completed the intervention with those obtained in patients who did not complete it. Results The rate of decline in the patients attending our program was 41.6% in the first year. Our results suggest that the Plutchik Impulsivity questionnaire, could be used as a predictive tool for success/attrition in intensive life style weight loss program. Conclusions Our results suggest that the Plutchik Impulsivity questionnaire, could be used as a predictive tool for success/attrition in intensive life style weight loss program. The screening of patients prior to inclusion in these programs should help to optimize its efficacy and efficiency.