The aim of this study was to evaluate the efficacy in the reduction of weight with a cetogenic very low calorie diet followed by alimentary reeducation according to the PronoKal® method in patients with overweight and obesity, and the safety during the procedure. Retrospective, observational and multicentre study where the patient's descriptive variables, variables related with the ponderal change, abdominal waist circumference, and general biochemistry were statistically analysed at the end of each treatment stages, and the adverse events referred at each visit during the treatment. From the 426 evaluable cases, 62.3% of the patients were obese. The 16.7% had hyperlipemia, the 2.3% type 2 diabetes mellitus, and the 4.8% arterial hypertension. At the end of treatment, the mean weight lost was 17.1 ± 8.0 kg (p < 0.001), with a BMI reduction of 6.2 ± 3.0 kg/m2. The 54.2% of the patients achieved the status of normoweight (35.9% of obese patients), higher in women than in men (62.5% vs 28.2%, respectively; p < 0.001). Waist perimeter was reduced in 17.3 ± 9.5 cm. There was an improvement in all laboratory variables in diabetic, hypertensive and dyslipemic patients, reaching statistical significance (p < 0.05) in glucose reduction (28.8%) in diabetics, in glucose (12.7%) and cholesterol (14.5%) reduction in hypertensive, and in glucose (11.7%), total cholesterol (14.5%), LDL cholesterol (11.3%) and triglycerides (37.9%) reduction in dyslipemics. The presence of adverse events was reported in 23.7% of patients, mainly constipation (23.9%). The PronoKal® method is an effective and safe method of excess weight approach, when it is done at completion and under a strict multidisciplinary medical control, improving different cardiovascular risk parameters.