*4.2. Population*

Volunteers were recruited on a voluntary basis from the Institute of Nutrition and Functional Foods contacts database, Laval University network, and Diabète Québec Association website. Inclusion criteria included age between 18–70 years, body mass index (BMI) ≥ 27 cm, waist circumference ≥ 94 cm for men and ≥80 cm for women, fasting insulin ≥ 60 pmol/L, fasting glycemia between 5.6–6.9 mmol/L or/and 2 h glucose in oral glucose tolerance test (OGTT) between 7.8–11.0 mmol/L or/and glycated hemoglobin A1C (HbA1C) between 5.7–6.4% for prediabetes diagnostics [52], and stable weight during the last 3 months. Exclusion criteria included type 2 diabetes, uncontrolled hypertension, thyroid disorders, renal and hepatic dysfunction, gastro-intestinal disorders, or other chronic or acute diseases. People who intake medications, food supplements, or natural health products that affect glucose and lipid metabolisms or body weight were also excluded. Major surgery during the last 3 months, smoking, pregnancy or breastfeeding, and allergies to fish, seafood, or iodine were also considered as exclusion criteria. A total of 260 subjects, recruited in the Québec City metropolitan area through media advertising, were screened to examine their eligibility to participate in this study (Supplementary Figure S1). During the first screening visit, two self-administered online questionnaires were completed by all subjects to collect information on medical history, lifestyle, economic and sociodemographic characteristics. Of 260 subjects, 125 subjects were excluded, and 11 decided not to participate. During the second screening visit, blood was collected from 124 subjects, and 58 subjects were also excluded from the study because they did not meet the plasma inclusion criteria. Thus, of 66 eligible volunteers after the two screening visits, 56 completed the study (Supplementary Figure S1) because ten subjects among the eligible volunteers no longer met inclusion criteria, dropped out, or refused to pursue the study for personal reasons during the study. During a 2-week run-in phase, the participants were asked to maintain their dietary routine and refrain from vigorous activity. After the 2-week run-in phase, the participants were randomly assigned to either the placebo group or the brown seaweed extract group, based on weight, BMI, and gender, and received individualized nutritional counseling for a moderate weight loss.
