BackgroundThe management of obesity should be multidimensional based on the choice of the treatment and the intensity of the therapeutic-rehabilitative intervention. This meta-analysis aims to compare the changes on body weight and body mass index (BMI) during an inpatient treatment (hospitalized weight loss programs with different durations in terms of weeks) compared with the outpatient phase.MethodsThe data obtained from the studies on inpatients have been layered into two categories: short term (studies with follow-up of max 6 months) and long term (studies with follow-up up to 24 months). Furthermore, this study evaluates which of the two approaches show the best impact on weight loss and BMI during 2 follow-ups at 6 to 24 months.ResultsThe analysis, which included seven studies (977 patients), revealed that the subjects underwent a short hospitalization had greater benefit, compared to those who were followed for a long time. The meta-analyzed mean differences for random effect (MD) showed a statistically significant decrease on BMI of −1.42 kg/m2(95% CI: −2.48 to −0.35;P= 0.009) and on body weight −6.94 (95% CI: −10.71 to −3.17;P= 0.0003) for subjects who carry out a short hospitalization compared to outpatients. No reduction of body weight (p= 0.07) and BMI (p= 0.9) for subjects who undergo a long hospitalization compared to an outpatient.ConclusionsA short-term inpatients multidisciplinary weight loss program could be the best choice for the management of obesity and its related comorbidities; on the contrary, if the follow-up is of long duration, the significance is not confirmed. The hospitalization at the beginning of any obesity treatment is significantly better than only outpatients treatment.