This paper concerns a cross-sectional population-based study conducted with adults living in the city of Pelotas, Rio Grande do Sul State, Brazil. It aims to determine the prevalence of weight-loss practices and use of substances for weight-loss during the 12 months preceding the interview. The prevalence of weight-loss attempts was 26.6%. Although dietary control and regular physical exercise were the most commonly used strategies, the prevalence of the combined use of these methods was only 36% for individuals trying to lose weight. The prevalence of use of substances for weight-loss was 12.8% (48.4% of those who tried to lose weight). The use of dietary control and substances was more common among women, while men practiced physical exercise with greater frequency. Teas were the most frequently used substances for weight-loss. Multivariate analysis identified being female, excess weight and self-perception of excess weight as major associated factors for the use of substances for weight-loss. Finally, we found that, although weight-loss attempts are common, the majority of obese individuals do not make attempts to lose weight and only a minority follows the recommended practices.