To evaluate the impact of pasteurized Akkermansia muciniphila Akk11 capsules versus placebo on body composition (including body weight, BMI, body fat percentage, waist-to-hip ratio, wrist circumference, visceral fat area, and basal metabolic rate) and serum lipid parameters (TC, LDL-C, HDL-C, and TG) in overweight and obese adults.

Inclusion Criteria:

1. Body mass index (BMI) ≥ 24 kg/m²;
2. Able and willing to provide written informed consent;
3. Willing to comply with the study protocol and required restrictions, including adherence to a low-carbohydrate, energy-restricted diet;
4. No intention to conceive from 14 days prior to screening until 6 months after study completion, and agreement to use effective contraception during this period

Exclusion Criteria:

1. Recent use of products with similar functions to the investigational product that may interfere with study outcomes;
2. History of psychiatric or neurological disorders, celiac disease, lactose intolerance, or known allergies;
3. Pregnant or breastfeeding women, or those planning to become pregnant during the study period;
4. Diagnosis of irritable bowel syndrome (IBS), ulcerative colitis, liver cirrhosis, or diabetes mellitus;
5. Use of antibiotics within 3 months prior to screening;
6. Inability to comply with the study protocol, including failure to take the investigational product as required or attend scheduled follow-up visits;
7. Smoking more than 10 cigarettes per day;
8. Any other condition that, in the opinion of the investigator, would make the participant unsuitable for the study.