Overweight and obesity have reached worldwide epidemic level. Both overweight and obesity are characterized by comorbidities such as cardio-metabolic risk factors (i.e., insulin resistance, type 2 diabetes, hypertension, dyslipidemia, low-grade inflammation) representing a major public health problem. Therefore, it is urgent to find a therapeutic solution to target all these metabolic disorders. Among the environmental factors able to influence the individual susceptibility to gain weight and to develop metabolic disorders associated with obesity, more and more evidence show that the trillions of bacteria housed in our gastro-intestinal tract (i.e, gut microbiota) influence host metabolism. The investigators recently discovered a putative interesting microbial candidate, namely Akkermansia muciniphila (Akk). More exactly, we found that the administration of Akkermansia muciniphila reduced body weight gain, fat mass gain, glycemia and inflammatory markers in diet-induced obese mice. Moreover, in overweight/obese patients with cardiovascular risk factors subjected to a calorie restriction diet (calorie restriction diet for 6 weeks and an additional 6 weeks of weight maintenance), a higher abundance of Akkermansia muciniphila was associated with a better cardio-metabolic status in these patients. The investigators also discovered that patients having more Akkermansia muciniphila in their gut before the calorie restriction exhibited a greater improvement in glucose homoeostasis, blood lipids and body composition after calorie restriction. These observations suggested that the administration of Akkermansia muciniphila in overweight or obese people could be a very interesting therapeutic solution. Currently, no human study has investigated the beneficial effects of Akkermansia muciniphila administration on obesity and metabolic disorders. The overall objective of this study is to evaluate the effects associated with the administration of live or heat-killed Akkermansia muciniphila on the metabolic disorders (insulin-resistance, type-2 diabetes, dyslipidemia, inflammation) related to overweight and obesity in humans.

Inclusion Criteria:

• Aged between 18 and 70 years old

• Caucasian

• Insulin resistance (based on HOMA single-value)

• BMI between 25 and 50 kg/m²

• Metabolic syndrome: presence of at least 3 of the following criteria

  • Hypertension (blood pressure ≥ 130/85 mm Hg or antihypertensive treatment)
  • Hypertriglyceridemia (triglyceridemia ≥ 150mg/dl)
  • Low HDL-cholesterol (HDL-cholesterol < 40mg/dl for males, 50mg/dl for females)
  • Visceral obesity (waist circumference > 102 cm for males, 88cm for females)
  • Fasting hyperglycemia (fasting glycemia ≥ 110mg/dl)

• Informed consent signed by the patient

Exclusion Criteria:

• Acute or chronic progressive or chronic unstabilized diseases
• Alcohol consumption (more than 2 glasses per day)
• Previous bariatric surgery
• Surgery in the 3 months prior the study or surgery planned in the next 6 months
• Pregnancy or pregnancy planned in the next 6 months
• More than 30 minutes of sports 3 times per week
• Consumption of dietary supplement (omega-3 fatty acids, probiotics, prebiotics, plant stanols/sterols) in the month prior the study
• Inflammatory bowel disease or irritable bowel syndrome
• Diabetic gastrointestinal autonomic neuropathy (such as gastroparesis or reduced gastrointestinal motility)
• Consumption of more than 30g of dietary fibers per day
• Vegetarian or unusual diet
• Lactose intolerance or milk protein allergy
• Gluten intolerance
• Medications influencing parameters of interest (antidiabetic drugs such as metformin, DPP-4 inhibitors, GLP-1 receptor agonists, acarbose, hypoglycemic sulfonamides,glinides, thiazolidinediones, SGLT2 inhibitors, insulin,lactulose, consumption of antibiotics in the 2 months prior the study, corticosteroids, immunosuppressive agents, statins, fibrate, orlistat, cholestyramine, ezetimibe)
• Glycated hemoglobin (HbA1c) > 7.5%

Subjects and physicians were both blinded to the treatment allocation.