MR Fat Quantification and Elastography During a Very Low-calorie-ketogenic Diet (Pronokal Method®) vs a Low Calorie Diet

Prospective, multicenter, open-label, randomized and controlled study of the effects of weight loss and reduced visceral fat on non-alcoholic fat infiltration into liver after a very low calorie ketogenic diet (VLCK diet) (Pronokal® Method) versus a hypocaloric diet, with a 6-month follow-up.

The investigators will include obese patients with BMI higher than 30 kg / m2 to follow a standardized multidisciplinary weight-loss program (PronoKal® Method), which consists of a very-low-calorie diet, into which natural foods are gradually reintroduced, accompanied by physical exercise and emotional support, versus hypocaloric diet.

The aim of this study are see the reduction of fatty liver, visceral fat and improvement of hepatic stiffness during the weight loss treatment.

Patients will be visited monthly and data will recorded on 4 occasions: pre-inclusion, initial visit, 2-months visit (end of ketosis) and 6-months visit.

Hepatic fatty infiltration and visceral fat will be scanned by MRI and hepatic stiffness will be assessed by MR Elastography at: baseline, 2 months and 6 months. Also will be recorded anthropometric data (weight, BMI, waist circumference) and complete blood tests.

Eligibility Criteria:
Inclusion Criteria:

* Patients of either sex, older than 18 years
* Obese patients with BMI equal or over 30kg/m2
* Patients who agree to participate and sign the Informed Consent

Exclusion Criteria:

* Pregnant or lactating women.
* Patients weighing over 140 kg (by limitation of the MRI device)
* Patients on anti-obesity drugs (eg, sibutramine, orlistat and liraglutide) or weight-interfering medications (eg, topiramate). In such cases a wash out period of 3 months is required.
* Patients with alcohol intake \> 20 g/day in women and \> 30 g/day in men.
* Patients with liver failure or with pathologies that may affect the liver
* Patients with other causes of liver steatosis: chronic viral hepatitis and/or drug intake (corticosteroids, estrogens, NSAIDs, calcium antagonists, amiodarone, tamoxifen, tetracyclines, chloroquine, antiretrovirals, perhexiline).
* Patients with eating disorders.
* Patients with any psychiatric disorder (eg schizophrenia, bipolar disorder, substance abuse, severe depression).
* Patients receiving dicumarinic anticoagulants (Sintrom®).
* Patients taking corticosteroids.
* Patients with severe kidney failure (gfr \<30).
* Patients with type 1 and type 2 diabetes mellitus.
* Patients with hemopathies, including coagulation disorders
* Patients with cardiovascular or cerebrovascular disease (of heart rate disorders, recent infarction \[\<6m\], unstable angina, decompensated heart failure, recent stroke \[\<6m\]).
* Patients in acute attack of gout.
* Patients with renal lithiasis verified by ultrasound.
* Patients with cholelithiasis verified by ultrasound.
* Patients with electrolyte imbalance, according to medical criteria.
* Patients with orthostatic hypotension.
* Patients with cancer or history of cancer who have not been discharged from oncology
* Patients who are not expected to attend follow-up visits