Diabetes, Obesity
Impact of Ketogenic and Mediterranean Diets on Gut Microbiota Profile and Clinical Outcomes in Drug-Naïve Patients with Diabesity: A 12-Month Pilot Study

A 12-month study compared the effects of a very-low-calorie ketogenic diet and a Mediterranean diet on gut microbiota and clinical outcomes in drug-naïve patients with diabesity (type 2 diabetes and obesity).
Eleven patients were assigned to either a very-low-calorie ketogenic diet (KETO group) or a Mediterranean diet (MEDI group). After two months, the KETO group transitioned to the Mediterranean diet, and both groups followed the same diet from month four onward.
Key Findings
Clinical Outcomes:
- At 6 months, the KETO group showed greater improvements than the MEDI group in metabolic markers:
- BMI decreased by 5.8 kg/m²
- Waist circumference decreased by 6.25 inches (15.9 cm)
- HbA1c decreased from 6.7% to 5.5%
- Triglycerides decreased from 158 to 95 mg/dL
- At 12 months, both groups regained some weight, with a more pronounced rebound in the KETO group, who had transitioned to the Mediterranean diet.
- Quality of life improved more in the KETO group, particularly during the very-low-calorie ketogenic diet.
Gut Microbiota Changes:
- At 6 months, the KETO group had a greater shift toward beneficial bacteria, including Akkermansia muciniphila and Christensenellaceae, while reducing taxa linked to metabolic disorders.
- At 12 months, most gut microbiota changes diminished but remained above baseline.
In this study a very-low-calorie ketogenic diet led to greater short-term metabolic and microbiota improvements, but benefits declined after transitioning to a Mediterranean diet. It may be effective as an initial intervention for diabesity, but long-term strategies require further research.