This study intends to study the effect of Akkermansia muciniphila on weight loss and the improvement of blood inflammation and metabolic indexes in obese patients with low Body Mass Index (BMI) through multi-center clinical studies, and for the first time to innovatively explore the weight loss mechanism of Akkermansia muciniphila by comparing the changes in brain function and fecal microbiota before and after intervention.

Inclusion Criteria:

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1) Age 18-65 years old; 2）28≤BMI≤35Kg/m2； 3) Willing and able to comply with the protocol during the study period, and be able to cooperate with the completion of various examinations during the trial. Written informed consent is provided prior to entry into study screening, and the patient has understood that the study can be withdrawn at any time from the study without any loss

Exclusion Criteria:

1. Pregnant or lactating women, in the reproductive period and not taking contraceptive measures;
2. Oral antibiotics in the past 1 month prior to enrollment;
3. No use of probiotic prebiotic products before 3 weeks of intervention;
4. people without a fitness fat loss program or history of gastric surgery during the intervention period;
5. Patients with severe gastrointestinal diseases;
6. Those who are known to be allergic to synbiotics or similar products;
7. Patients with no self-awareness and those with mental abnormalities;
8. Have a history of organ transplantation or malignant tumor disease;
9. Concurrent use of other experimental drugs or in other clinical trials;
10. Have a history of alcohol, tobacco and other drug abuse;
11. Those who are expected to be unable to complete the magnetic resonance examination;
12. Combined with serious medical diseases or conditions: such as clinically serious (i.e., active) cardiac disease, severe, uncontrolled medical diseases and infections, severe uncontrollable digestive disorders, severe electrolyte disorders, active disseminated intravascular coagulation, major organ failure, such as decompensated heart, pulmonary, hepatic, renal failure, peripheral neuropathy symptoms, etc.

Double(participant, investigator)