OBJECTIVES: Obesity increases the risk of chronic diseases, with consequences on social cost and Quality of Life (QoL). Our objective was to estimate the social cost and QoL in overweight, obese and severe obese people. METHODS: A Cost-of-Illness study was conducted from the societal perspective, adopting three-month retrospective observational period. Data were collected from a population based naturalistic survey investigating cardiovascular risk factors in adult (40-79 y.o.) Italian general population. We selected normal weight people as control group (Body Mass Index, BMI = 18.5-24.9), overweight (BMI = 25.0-29.9), obese (BMI = 30.0-34.9) and severe obese (BMI >35.0) people, interviewed by general practitioners on clinical/demographic characteristics, direct costs (drugs, hospitalisations, specialist visits, diagnostics exams) and indirect costs (productivity loss). QoL was evaluated with the EQ-5D questionnaire. RESULTS: Data from 620 people were analyzed (mean age=58.2, 46.5% men). Total cost in overweight, obese or severe obese people was quantified as twice than in normal weight people (>200 vs. 111€/person/month). Direct cost involved more than half of total expense: hospitalizations accounted for the greatest part of direct cost, followed by drugs, diagnostic exams, medical visits and laboratory exams. Globally, the Visual Analogue Scale mean score was higher in overweight than in normal weight people, and lower in obese and severe obese people. Most of people reported no problem in “mobility”, “self care” and “usual activities” (around 90%), with “pain/discomfort” and “anxiety/depression” (around 50%). Very few people (<5%) reported extreme problems in any domains. Problems with physical component of QoL increased with BMI increase, while for “pain/discomfort” and “anxiety/depression”, normal weight and severe obese people complained more than overweight and obese people. CONCLUSIONS: obesity is expensive for the health care system and society and compromises individuals’ QoL. Policy makers should pay attention to identification, promotion and implementation of programs aimed at preventing obesity.