The FLOW (First Loss Of Weight) study is designed to assess the effects of repeated administration of GSP3, an investigational product, on body weight. It is a multicenter, randomized, double-blind, placebo-controlled, parallel-group, fixed-dose study. FLOW is being conducted in 5 medical centers in Italy, Czech Republic, and Denmark, and will randomize 123 overweight and obese adult males and females to receive either placebo, GSP3 (2.25g), or GSP3 (3.75g) in addition to a hypocaloric diet (-600 kcal/day) for 12 weeks.

Inclusion Criteria:

1. Body Mass Index (BMI) ≥ 27 and ≤ 35 (at least 30% overweight and 30% obese subjects)
2. Ability to follow verbal and written instructions
3. Informed Consent Form signed by the subjects

Exclusion Criteria:

1. Pregnancy or lactation
2. Absence of medically approved contraceptive methods in females of childbearing potential (e.g., hysterectomy, non-oral contraceptive medications or intrauterine device combined with a barrier method, two combined barrier methods such as diaphragm and condom or spermicide; bilateral tubal ligation and vasectomy are not acceptable contraceptive methods)
3. History of allergic reaction to carboxymethylcellulose, citric acid, modified cellulose, microcrystalline cellulose, and gelatin
4. Administration of investigational products within 1 month prior to Screening Visit
5. Night-shift workers
6. Subjects who stopped smoking within 6 months prior to Screening Visit or considering smoking cessation during the study
7. Subjects anticipating surgical intervention during the study
8. Known type 1 or type 2 diabetes
9. History of eating disorders including binge eating (except mild binge eater)
10. Weight change > 3 kg within 3 months prior to and during the Screening period
11. Supine systolic blood pressure (SBP) > 150 mm Hg and/or supine diastolic blood pressure (DBP) > 90 mm Hg
12. Angina, coronary bypass, or myocardial infarction within 6 months prior to Screening Visit
13. History of gastroesophageal reflux disease
14. History of gastric or duodenal ulcer
15. History of gastroparesis
16. History of gastric bypass or any other gastric surgery
17. History of intragastric balloon
18. History of pancreatitis
19. History of hemorrhoids
20. History of malabsorption
21. Laxative users
22. History of hepatitis B or C
23. History of human immunodeficiency virus
24. History of cancer within the past 5 years (except adequately-treated localized basal cell skin cancer or in situ uterine cervical cancer)
25. Any other clinically significant disease interfering with the assessments of Attiva, according to the Investigator
26. Positive serum or urine pregnancy test(s) in females of childbearing potential
27. Plasma glucose ≥ 126 mg/dL (7.0 mmol/L)
28. Abnormal serum thyrotropin (TSH)
29. Serum triglycerides > 500 mg/dL (5.65 mmol/L)
30. Positive test for drugs in the urine
31. Any relevant biochemical abnormality interfering with the assessments of Attiva, according to the Investigator
32. Anti-obesity medications (including herbal preparations) within 1 month prior to Screening Visit
33. Systemic corticosteroids within 1 month prior to Screening Visit
34. Thyroid hormones or preparations within 1 month prior to Screening Visit (except in subjects on stable dose of replacement therapy for at least 1 month)
35. Any other medication known to cause weight loss or weight gain within 1 month prior to Screening Visit
36. Medications treating hypertension within 1 month prior to Screening Visit
37. Medications treating dyslipidemia within 1 month prior to Screening Visit
38. Anticipated requirement for use of prohibited concomitant medications