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Inclusion Criteria:

* Age 18 to 65 years, inclusive.
* Body mass index of 25.0 to 40.0 kg/m2 at screening.
* No previous diagnosis of prediabetes or diabetes.
* Glycated hemoglobin (HbA1c) below 5.7% at screening.
* Fasting plasma glucose below 100 mg/dL at screening.
* Stable body weight, defined as a self-reported absolute change of no more than 5% or 3 kg, whichever is smaller, during the 3 months before screening.
* Willing and able to provide written informed consent.
* Willing and able to comply with study visits, assigned supplement or placebo use, and the assessment schedule.
* Willing to provide fasting venous blood and stool samples according to the study schedule.
* Willing to receive standardized lifestyle counseling during the 24-week blinded intervention period.
* No systemic antibiotic use within 8 weeks before randomization.
* No probiotic, prebiotic, synbiotic, or postbiotic supplement use within 12 weeks before randomization.
* If hypertension or dyslipidemia is present, antihypertensive or lipid-lowering treatment must have been initiated and the dose must have remained unchanged for at least 3 months before randomization, with no treatment change planned at the time of randomization.

Exclusion Criteria:

* Prediabetes or diabetes identified by medical history, HbA1c, or fasting plasma glucose.
* Use of glucose-lowering medication, including metformin, a glucagon-like peptide-1 receptor agonist, a glucose-dependent insulinotropic polypeptide/glucagon-like peptide-1 co-agonist, a sodium-glucose cotransporter-2 inhibitor, a dipeptidyl peptidase-4 inhibitor, a sulfonylurea, insulin, or another antidiabetic agent.
* Use of a glucagon-like peptide-1 receptor agonist or glucose-dependent insulinotropic polypeptide/glucagon-like peptide-1 co-agonist for any indication within 12 months before randomization.
* Use of another anti-obesity medication, including orlistat, naltrexone/bupropion, or phentermine/topiramate, within 6 months before randomization.
* Planned initiation during the 24-week study of a weight-loss medication, structured commercial weight-loss program, very-low-calorie diet, or bariatric procedure.
* History of bariatric surgery.
* History of gastrointestinal surgery other than appendectomy or uncomplicated cholecystectomy.
* Active inflammatory bowel disease, celiac disease, microscopic colitis, chronic pancreatitis, malabsorption syndrome, or another chronic severe gastrointestinal disease likely to affect nutrient absorption or study adherence.
* Acute gastroenteritis within 4 weeks before randomization.
* Colonoscopy bowel preparation within 12 weeks before randomization.
* Fecal microbiota transplantation within 12 months before randomization.
* Active malignancy or malignancy treated within 6 months before screening, except adequately treated non-melanoma skin cancer.
* Stage 3b to 5 chronic kidney disease, defined as an estimated glomerular filtration rate below 45 mL/min/1.73 m2.
* Decompensated liver disease or Child-Pugh class B or C liver disease.
* Alanine aminotransferase or aspartate aminotransferase greater than 3 times the upper limit of normal at screening, unless judged clinically insignificant and approved by the investigator.
* Untreated overt thyroid disease, or initiation or dose modification of thyroid medication within 3 months before randomization. Stable treated hypothyroidism is permitted.
* Use of systemic corticosteroids within 4 weeks before randomization.
* Use of immunosuppressive medication or biologic or immunomodulatory therapy within 5 half-lives before randomization.
* Pregnancy or lactation.
* For participants of childbearing potential, unwillingness to use effective contraception during the 24-week blinded intervention period.
* Severe psychiatric illness or cognitive impairment that, in the investigator's judgment, would impair informed consent, participant safety, or adherence to study procedures.
* Active eating disorder, defined as at least 2 affirmative responses on the SCOFF screening questionnaire or a clinical diagnosis of anorexia nervosa, bulimia nervosa, or binge-eating disorder.
* Heavy alcohol use or active substance use disorder.
* Current use of a very-low-calorie diet, ketogenic diet, medically supervised weight-loss diet, or another highly restrictive diet that excludes major food groups.
* Current cigarette smoking with a stated intention to attempt smoking cessation during the 24-week study, or initiation of nicotine-replacement or other smoking-cessation pharmacotherapy within 3 months before randomization.
* Participation in another interventional clinical study within 30 days before screening.
* Known hypersensitivity or clinically significant intolerance to any component of the active supplement or placebo.
* Any condition that, in the investigator's judgment, would compromise participant safety, adherence, or study integrity.

• Istanbul, Turkey (Türkiye)