Based on our hypothesis that orally administered GOS will be fermented into a SCFA pattern high in acetate and that this will lead to beneficial effects on human substrate and energy metabolism, we aim to address the following primary objective:

To investigate the effects of a 12-week supplementation of GOS on peripheral insulin sensitivity and body weight control in obese adults with impaired glucose homeostasis.

Inclusion Criteria:

Overweight/obese (BMI ≥ 28 kg/m2 < 40 kg/m2) insulin impaired men and post-menopausal women with impaired glucose tolerance (IGT: 2h plasma glucose during 75g OGTT 7.8-11.1 mmol/l) and/or impaired fasting glucose (plasma glucose ≥ 5.6 mmol/l) aged 45-70 years will be included in the study.

In addition, subjects have to be weight-stable for at least 3 months prior to participation (no change in bodyweight, i.e. < 3kg).

Exclusion Criteria:

• diabetes mellitus
• gastroenterological diseases or major abdominal surgery (allowed i.e.: appendectomy, cholecystectomy)
• lactose intolerance and other digestive disorders
• cardiovascular disease, cancer, liver or kidney malfunction (determined based on ALAT and creatinine levels, respectively)
• disease with a life expectancy shorter than 5 years
• abuse of products (alcohol consumption > 15 units/week, or any drugs)
• excessive nicotine use defined as >20 cigarettes per day