Kidney transplant recipients (KTR) have a considerably lower life expectancy as compared with the general population, primarily due to a high prevalence of cardiovascular diseases. KTR often develop an unfavourable cardio-metabolic risk profile characterized by weight gain, metabolic syndrome and post-transplantation diabetes mellitus (PTDM). In general, nutrition plays a key role in both the prevention and treatment of these cardio-metabolic derangements.

However, in KTR most RCT's with a dietary intervention, failed to show significant improvement in cardio-metabolic health. This at least questions the efficacy of the diets of these intervention, which relied on general or diabetes guidelines, after kidney transplantation. KTR not only face a high cardio-metabolic risk, but also have a high risk for malnutrition and muscle mass depletion. More knowledge is required to determine the optimal diet and macronutrient composition for improvement of the cardio-metabolic risk factors in the context of the high malnutrition risk. In this regard, observational studies point towards the needs for a higher protein intake for better patient outcomes. Therefore, in this study, the investigators will examine if a high-protein, carbohydrate-reduced diet is more effective than a diet in line with the Dutch Dietary Guidelines for improvement of cardio-metabolic risk factors and for improvement of the body composition in KTR.

Inclusion Criteria:

• Age 18 years or older.
• Given informed consent.
• At least 6 months after kidney transplantation.
• Stable renal function with an estimated glomerular filtration rate (eGFR) > 30 mL/min.
• Raised systolic blood pressure (≥130 mmHg) and at least two more features of metabolic syndrome: central obesity (waist circumference ≥102 for men and ≥88cm for women), elevated triglycerides (≥ 1.7 mmol/L), reduced HDL-C (< 1.0 mmol/L for men and < 1.3 mmol/L for women) or on drug treatment for reduced HDL, elevated plasma glucose (≥ 5.6 mmol/L) or on drug treatment for elevated glucose9.
• Approval by nephrologist for participation in the study.

Exclusion Criteria:

• Active medical illness, including rejection of the graft.
• Psychopathology or serious cognitive impairment.
• Necessity to follow specific dietary measures for health purposes that conflict with the study diets.
• Use of insulin or sulfonylurea (SU)-derivates.
• Language barrier.
• Pregnancy or lactating.
• Serum potassium > 5.0 mmol/L that requires dietary measures.
• Moderate or severe malnutrition (Patient-Generated Subjective Global Assessment (PG-SGA) stage B or C). In this case, patient will be referred to a renal dietician.
• Participation in other intervention trials.