Acute Microbial Switch

Inclusion Criteria: Lean normoglycemic individuals: Lean (BMI ≥ 18.5 kg/m2 and ≤ 24.9 kg/m2 ); Normal fasting glucose (plasma glucose < 5.6 mmol/L) and a HOMA-IR< 2.2 Individuals with overweight/obesity and prediabetes/insulin resistance: Overweight/obesity (BMI ≥ 28 kg/m2 and ≤ 40 kg/m2 ); insulin resistance (HOMA-IR>2.2) and/or impaired fasting glucose (IFG: plasma glucose ≥ 5.6 mmol/l) For both subject groups: Aged 30 - 75 years; Normal blood pressure (systolic blood pressure 100-150mmHg, diastolic blood pressure 60-100 mmHg); Weight stable for at least 3 months (± 2 kg) Exclusion Criteria: T2DM (defined as fasting plasma glucose ≥ 7.0 mmol/L) Gastroenterological diseases Abdominal surgery affecting the GI tract; Cardiovascular diseases, cancer, liver or kidney malfunction, disease with a life expectancy shorter than five years; Abuse of products; Alcohol (> 15 standard units per week) Drugs Excessive nicotine use defined as >20 cigarettes per day; Plans to lose weight or following of a hypocaloric diet Regular supplementation of pre- or probiotic products, use of pre- or probiotics three months prior to the start of the study; Intensive exercise training more than three hours a week; Use of most medications that influence glucose or fat metabolism, like some lipid lowering-drugs (e.g., PPAR γ or PPARα (fibrates) agonists), glucose-lowering agents (including all sulfonylureas, biguanides, α-glucosidase inhibitors, thiazolidinediones, repaglinide, nateglinide and insulin), inflammation (e.g., anti-inflammatory* or immunosuppressive drugs) and anti-oxidants; Regular use of laxatives; Use of antibiotics in the last three months (antibiotics use can alter substantially the gut microbiota composition). Veganism Lactose intolerance For women: pregnancy or lactation