RESUMEN
INTRODUCTION: Changes in unhealthy lifestyles are key elements in the prevention and treatment of obesity and hypertension. Internet-based programs offer great potential for the implementation of evidence-based interventions focused on promoting healthy habits. We evaluate the efficacy of an Internet-based self-administered program ("Living Better") that addresses people diagnosed as being overweight or having type I obesity and hypertension. METHODS: The sample was composed of a total of 106 participants (age Mean = 53; 59 males) from a public hospital in Spain, diagnosed as being overweight or having type I obesity and hypertension and randomized into two groups-the intervention group (IG; Internet-based intervention) and the control group (CG; usual medical treatment). The intervention used cognitive-behavioral strategies and psychoeducation to promote healthy habits. Anthropometric data (i.e., Body Mass Index -BMI-, waist circumference, and hip circumference) and lifestyle/psychological data (i.e., quality of life, physical activity, eating styles, motivation, mood, and self-efficacy) were assessed before and after the intervention, and at 6 and 12-month follow-ups. RESULTS: Significant differences were observed between the IG and the CG in anthropometrical variables after intervention (i.e., BMI and waist circumference), external eating style, and anxiety and stress scores (p < 0.05). Follow-up data showed that changes were maintained in BMI, waist and hip circumference, and external eating in the IG. After receiving the Internet-based treatment, the CG also improved its clinical condition. DISCUSSION: This study demonstrates that the Internet is a viable alternative for the delivery and dissemination of interventions focused on promoting healthy habits, and a totally self-administered intervention can produce long-term positive results.