Effect of a Very Low-Calorie Ketogenic Diet on Gut Microbiota and Fat Distribution
Condition: Obesity
Study type: Interventional

Summary: 
      Short-term interventions that use very low-calorie ketogenic diets and meal replacements may
      be prescribed for selected overweight or obese patients with type 2 diabetes or prediabetes.
      Few, inconsistent data are available on protein intake from various sources on body weight,
      the composition of gut microbiota and metabolic outcomes in these patients. The aim of the
      present study is to compare efficacy, safety and effect on microbiota composition of
      short-term isocaloric VLCKDs using whey proteins, vegetable proteins or animal proteins in
      obese patients with diabetes or prediabetes. 50 obese diabetic/prediabetic patients will be
      randomly assigned to three isocaloric VLCKD regimens (≤800 kcal/day) containing either whey,
      plant or animal proteins for 45 days. Outcome measures will be anthropometric parameters,
      vital signs, metabolic profile, body composition and microbiota assessment.
    

Detailed description: 
      Short-term interventions that use very low-calorie ketogenic diets and meal replacements may
      be prescribed for selected overweight or obese patients with type 2 diabetes or prediabetes.
      Few, inconsistent data are available on protein intake from various sources on body weight,
      the composition of gut microbiota and metabolic outcomes in these patients. The aim of the
      present study is to compare efficacy, safety and effect on microbiota composition of
      short-term isocaloric VLCKDs using whey proteins, vegetable proteins or animal proteins in
      obese patients with diabetes or prediabetes. 50 obese diabetic/prediabetic patients will be
      randomly assigned to three isocaloric VLCKD regimens (≤800 kcal/day) containing either whey,
      plant or animal proteins. Outcome measures will be anthropometric parameters, vital signs,
      metabolic profile, body composition and microbiota assessment. The patients will be assessed
      at baseline (T0) and every two weeks (T15, T30) up to day 45 (T45) when they will be finally
      evaluated. Patients will be given support and counselling to enhance their compliance. The
      patients will also be instructed to have moderate-intensity physical activity (e.g., 30
      minutes walking every day) during the study.

      Anthropometric parameters Body weight, blood pressure (systolic and diastolic), heart rate,
      waist and hip circumference will be measured at baseline (T0), every two weeks up to the end
      of the trial (T45).

      Blood and urine chemistry Complete Blood Count (CBC), electrolytes (chloride, calcium,
      potassium, sodium, magnesium), fasting glucose, insulin, lipids (total and fractionated
      cholesterol and triglycerides) and proteins, C-reactive protein (CRP) and erythrocyte
      sedimentation rate (ESR), plasma creatinine, blood urea nitrogen (BUN), alanine transferase
      (AST), aspartate transaminase (ALT), uric acid and estimated Glomerular Filtration Rate
      (using the Modification of Diet in Renal Disease study equation MDRD-eGFR) will be determined
      at baseline and after 45 days.

      The overnight fasting plasma levels of Insulin Like Growth Factor-1 (IGF-1) will be measured
      using commercially available ELISA kits. Urine tests will be performed at baseline and every
      other week until the end of the study.

      Dual-Energy-X-ray Absorptiometry measurement (DEXA) Body composition, total and regional body
      fat mass (FM) and fat-free mass (FFM), will be measured using DEXA (Hologic 4500 RDR) at
      baseline and at the end of the trial.

      Visceral adipose tissue (VAT) will be calculated using a fully automated software. DEXA-VAT
      will be measured in a 5 cm wide area placed in the abdominal region just above the iliac
      crest, at a level that approximately coincides with the 5th lumbar vertebrae on the whole
      body DEXA scan. The VAT will be estimated by subtracting subcutaneous fat from the total
      abdominal fat by means of an algorithm.

      Muscular strength Muscle strength will be measured through a digital dynamometer handgrip at
      T0 and T45. Before starting, patients will be asked to squeeze as hard as possible the
      dynamometer for at least 3 seconds. Three measurements will be repeated with both the
      dominant and non-dominant arms. The highest value measured will be recorded as the maximum
      grip force.

      Taxonomic composition of the gut microbiome Fecal sampling will be done using sterile swab
      and tubes DNA purity will be evaluated based on A260/A280 ratio using a spectrophotometer.
      DNA integrity and size will be assessed by 1.5% agarose gel electrophoresis. The V3-V4 region
      of the 16S ribosomal RNA gene will be amplified. Polymerase Chain Reaction (PCR) amplicons
      will be purified and amplified following the Nextera XT Index protocol. The processed reads
      will be clustered and the operational taxonomic units will be assigned to taxa.

      Data obtained will be expressed as mean values ±Standard Deviation (SD) and finally processed
      to ascertain whether statistical differences among them can be demonstrated, using
      appropriate methods. In particular, the analysis of variance (ANOVA) at different times will
      be used for efficacy and safety data, such as weight reduction, changes in anthropometric
      measures, FM and FFM and variation of the metabolic parameters. P values <0.05 will be
      considered statistically significant.
    

Intervention name(s): Whey protein, vegetable protein or animal protein
Intervention type(s): Dietary Supplement
Intervention description(s): meal replacements or animal protein
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment