© 2018 Sociedad espanola de dietetica. All rights reserved. Introduction: The obesity is a public health problem that in recent years has increased in the adult population. Objective: To determine the impact of an educational intervention on the reduction of overweight and obesity in administrative workers of a private company of construction. Methods: A before and after study, with baseline evaluation before of the intervention, It was based on the implementation of healthy lifestyles, nutritional monitoring and the promotion of physical activity in the workplace for two years. Non-probabilistic sampling, 84 workers were included. The informed consent was verbal. Averages, percentages, student t for paired samples, wilcoxon and the Stuart-Maxwell test were calculated to evaluate the effect of the intervention. The intervention was carried out within the framework of occupational health activities implemented in the company. Results: It was found that the average weight in the pre-intervention stage was 75.3 kg and the average post-intervention weight was 71.6 kg. In the pre-intervention stage, 76.5% (65/85) were overweight or obese, while in the post-intervention stage, 51.8% (44/85) were overweight or obese, evidencing a 24,7% decrease during the intervention (p value <0.001). It was also observed that overweight decreased in women from 60.4% to 55.6% (4.8 pp) and obesity was reduced in men from 47.1% to 37.5% (9.6 pp). Discussion: Interventions based on changing healthy lifestyles decreased overweight and obesity in workers. Conclusions: The educational intervention improved nutritional status, mainly obesity and overweight, increasing the percentage of workers with normal nutritional status.