Main aim: Study the anthropometric, metabolic, cardiovascular and neurocognitive and gut microbiota changes of different approaches for the weight reduction that increase the ketone bodies in a different proportion in relation to the classic hypocaloric diet.

Objective 1: Study the effect of hypocaloric diets that increase the ketone bodies on gut microbiota and its relationship with anthropometric changes and of the Brown adipose tissue, Objective 2: with the metabolic and inflammatory changes, Objective 3: on the cardiovascular system, Objective 4: on the neurocognition, Objective 5: if they are associated to epigenetic changes that may explain the changes found in the other objectives. Objective 6: Determine the safety of the diets that increase the ketone bodies compared to the classic hypocaloric diet, Objective 7: if the effects of the different dietary approaches are maintained during the medium time, and Objective 8: Verify in experimental models (microbiota transplants from humans with different diets to germ-free mice, ketosis dietary models, and ketone bodies administration) the causality of the gut microbiota of these findings.

Methodology: Model 1: Dietary intervention in humans with 4 types of diet with a different increase of the ketone bodies: classic hypocaloric diet (DH); diet with 8h of feeding and 16h of starving in periods of 24h (D16); diet with intermittent caloric restriction (DA); and normal in protein and low in carbohydrates hypocaloric ketogenic diet (DC).

Inclusion Criteria:

• Obesity (BMI≥30-45 kg/m2)

Exclusion Criteria:

• Type 2 diabetes mellitus
• Patients with major cardiovascular events in the 6 months prior to the study beginning.
• Previous or current history of inflammatory disease.
• Active infectious disease.
• The refusal of the patient to participate in the study
• Consumption of probiotics or prebiotics
• Antibiotic therapy in the 3 months prior to the study