The overall goal of IMOAP study is to assess whether the efficacy of the healthcare professionals' usual practices, together with a motivational group intervention (delivered by a nurse trained by an expert psychologist), is more effective than an isolated traditional intervention on weight loss and its maintenance in overweight and obese patients. Furthermore, the study will evaluate whether this result has a positive impact on quality of life, changes in eating habits, and a reduction in the associated cardiovascular risk factors and overall cardiovascular risk.