Dietary Intervention in Obesity-related Glomerulopathy

Obesity-related glomerulopathy (ORG) is a silent comorbidity associated with obesity whose incidence is increasing in parallel to the obesity epidemic. ORG is associated with serious health consequences including chronic kidney disease, end-stage renal disease, and increased mortality. Unfortunately, ORG has an absence of targeted therapy (except for the use of drugs blocking the renin-angiotensin system), and therefore the prognosis of this disease may be seriously compromised. Some previous studies have shown that weight loss could be effective to decrease albuminuria and reduce the declining in kidney function in subject with obesity. In line with this, in this study the investigators will evaluate the efficacy of two different dietary strategies for ORG, given the current lack of therapies for this condition. Thus, the investigators will conduct an open-label randomized controlled trial comparing a hypocaloric Mediterranean diet with a very-low calorie diet (VLCD), evaluating the efficacy on albuminuria reduction and changes in renal function. Also, the investigators will assess changes on body composition, blood pressure, markers of renal damage and inflammation, gut microbiota, and on renal ultrasound elastography.

Our hypothesis is that a dietary strategy based on a very low calorie diet (VLCD) will produce a greater reduction in albuminuria than a hypocaloric Mediterranean diet in subjects with ORG. This improvement will be achieved through weight loss and changes in body composition, the reduction of blood pressure, the decrease in inflammatory, tubular and podocyte damage markers, modifications in adipokine concentrations, changes in the intestinal microbiota and in renal elastography.

The main objective of this clinical trial is to evaluate which dietary strategy (VLCD diet or Mediterranean hypocaloric diet) is more effective in reducing albuminuria and preserving renal function in patients with ORG.

Eligibility Criteria:
Inclusion Criteria:

* BMI ≥ 30 kg/m2
* Albuminuria ≥ 150 mg/g
* eGFR ≥ 30 ml/min/1,73 m²
* Informed consent signed
* All patients should receive a stable dose of ACE inhibitors or ARBs for at least 4 weeks prior to randomization. Before randomization; A stable dose will be considered to be the maximum dose indicated in the drug's SmPC or a dose that is not associated with unacceptable side effects in the patient.

Exclusion Criteria:

* Previous diagnosis of diabetes mellitus (defined by HbA1c ≥ 6.5% or baseline blood glucose ≥126 mg / dl or blood glucose 2 hours after oral glucose overload ≥200 mg / dl).
* Treatment with oral hypoglycemic agents, insulin or GLP-1 receptor agonists.
* Active cancer
* History of liver tumor or acute or chronic liver diseases with impaired liver function: total bilirubin levels\> 2.0 mg / dL or AST levels three times higher than the upper limit of normal.
* Established cardiovascular disease (stroke, acute myocardial infarction, cardiac revascularization).
* Uncontrolled hypertension (systolic blood pressure\> 180 mmHg or diastolic blood pressure\> 110 mmHg) despite adequate antihypertensive treatment.
* Infection with HIV, HBV, HCV or other infection that can lead to secondary glomerular disease
* Suspicion of primary glomerulopathy (except GAO).
* Evidence of drug or alcohol abuse.
* Serious underlying conditions that, in the opinion of the investigators, could affect the patient's ability to participate in the study.
* Limited life expectancy (\<12 months).
* Pregnancy or breastfeeding.
* Impossibility of following the indicated diet.
* Inability to follow scheduled visits.