Introduction Increasing prevalence of obesity worldwide reinforces the importance of studying weight-loss habits of the population. It is known that lifestyle modifications (LSM) should be the mainstay of overweight treatment and that use of drugs should be considered adjuvant in the process. Despite weight-loss attempts being common practices and Brazil being considered a major consumer of anorectic drugs, population-based studies are still scarce.

Methods Between January and May 2010 we conducted a cross-sectional population-based study with household interviews among adults in Pelotas, a medium size city located in southern Brazil, to determine the prevalence of weight-loss attempts in the last year and identify substances most commonly used.

Results Data were collected from 2732 individuals, with a rate loss of 10.3%. Overall prevalence of anti-obesity agents use was 4.8% (4.0 to 5.7), being higher in women (7.3%, CI 6.0 to 8.6) and among those of higher schooling (9.3%, CI 7.0 to 11.7). Drugs mainly used were: sibutramine (45.5%) amphetamines (31.8%) and herbal medicines (25.0%). Weight-loss formulae containing combinations of drugs, illegal in Brazil, were reported by 6.1% of users. Only 39.4% of drugs users referred to add dietary changes and regular exercise, and 47.0% slimming teas.

Conclusion Despite the regulations, medical prescription was just reported by 49.6% of the users. Moreover, we found a high prevalence of cardiovascular risk factors among users of sibutramine and amphetamines (hypertension: 30.9%; Hypercholesterolaemia: 27.7%; Diabetes: 10.8%; Age >40 years: 36.6%; Smoking: 10.4%) with 5% of sibutramine users reporting previous myocardial infarction or angina, contra indications for it usage.