This is a prospective, single-center, randomized, open-label, parallel-controlled clinical trial to compare the changes in brain function after intragastric balloon and sleeve gastrectomy.

To compare the changes in brain function in obese patients after intragastric balloon and sleeve gastrectomy. This clinical trial is a prospective, single-center, randomized, open-label, parallel-controlled study. One group uses intragastric balloon system developed by Changzhou Zhishan Medical Technology Co., Ltd, and the other groups underwent sleeve gastric surgery. Before patients are enrolled in this clinical study, the researchers will do a detailed screening of the subjects based on the inclusion criteria and the exclusion criteria to determine if the patients are appropriate for the clinical study. Patients who meet the conditions of the study will be required to sign an informed consent form. They are divided into different groups according to their own wishes. To evaluate the primary outcome measures and secondary outcome measures and to observe the changes in brain function. Finally, investigators used functional MRI, questionnaire, and laboratory examination to evaluate the weight loss effect and appetite change through the comparison of the data obtained from the different groups during the treatment.

Inclusion Criteria:

18 ≤ age ≤ 65, regardless of gender;

• BMI ≥ 27.5kg/m2 and ≤ 40kg / m2;
• Those who have tried other weight loss methods in the past but are not satisfied with the results;
• Willingness to comply with the study requirements, including willingness to avoid the use of drugs or other substances for weight loss during the follow-up study;
• Right handed, avoid using antibiotics and probiotics within 3 month before enrollment;
• Be able to take proton pump inhibitors and antiemetics according to the regulations of the researcher;
• It can walk completely independently without any serious chronic orthopedic diseases;
• Be willing to avoid the use of non-steroidal anti-inflammatory drugs during the study, including aspirin, diclofenac, ibuprofen, naproxen or other known gastric irritants;
• Willing to accept gastroscopy;
• Voluntarily participate in the trial and sign the informed consent form.

Exclusion Criteria:

• Patients with previous or current diagnosis of ketoacidosis;
• Symptomatic congestive heart failure, arrhythmia or unstable coronary artery disease;
• Currently suffering from respiratory diseases such as chronic obstructive pulmonary disease (COPD), pneumonia or lung cancer;
• Have undergone weight loss surgery before enrollment in the study, or may have undergone weight loss surgery during the study;
• Before the study, he used intragastric medical devices to lose weight;
• Had acute or chronic pancreatitis within 12 months before enrollment;
• Previous or current history of small bowel obstruction
• Obesity caused by genetic endocrine reasons (test results of cortical hormone and thyroid hormone, clinically significant abnormalities determined by the researcher) and not fully controlled by drugs;
• Esophageal, gastric or duodenal diseases (including hiatal hernia (≥ 2cm), paraesophageal hernia, polyps, acute erosive gastritis, cancer, varices, diverticulum, gastroparesis, ulcer, stenosis, achalasia of cardia complicated with esophagitis, etc.);
• Systemic corticosteroid anticoagulants (such as warfarin, dabigatran or antiplatelet drugs), immunosuppressive drugs (such as imidazole thiopurine, cyclosporine), prescription or over-the-counter weight loss drugs, drugs known to cause significant weight gain or weight loss, such as anesthetics, opioids or diazepines), insulin Antiepileptic drugs (such as clonazepam and phenytoin sodium), antiarrhythmic drugs (such as amiodarone); Other drugs that may cause weight change include: drugs that can significantly increase weight (such as glucocorticoids, insulin secretagogues, thiazolidinediones, atypical antipsychotics, sodium valproate, lamotrigine, antidepressants), and drugs that can significantly reduce weight (such as glucagon like peptide-1 receptor agonists α- Glucosidase inhibitor, zonisamide, topiramate, fluoxetine, bupropion, etc.);
• Night eating syndrome or bulimia;
• Unwilling to avoid any reconstruction and / or plastic surgery that may affect body weight during the study, such as mastoplasty and liposuction;
• Patients with inflammatory bowel disease (such as Crohn's disease and ulcerative colitis);
• Previous history of malignant tumor;
• Women of childbearing age whose pregnancy test is not negative before examination, lactating women, or who plan to conceive within half a year;
• Past or current drug or alcohol abuse.