Based on previous research of the investigators group, the investigators hypothesize that slowly fermentable fibers with a high degree of polymerization that increase SCFA specifically in the distal colon are expected to have higher potential for influencing host metabolism and metabolic health by improving adipose tissue function, preventing lipid overflow and hepatic as well as skeletal muscle fat accumulation thereby improving insulin sensitivity.

The objective of this randomized clinical trial is to test, whether the a dietary fiber product containing different physiological acting fibers reverses peripheral and hepatic insulin resistance in overweight/obese insulin resistant participants.

Inclusion criteria:

Overweight/obese insulin resistant/prediabetic participants (age 45-70 y, BMI ≥ 28 kg/m2 < 35 kg/m2)

Exclusion criteria:

• Type 2 diabetes mellitus (defined as fasting plasma glucose ≥ 7.0 mmol/L and 2h glucose ≥ 11.1 mmol/L)
• Gastroenterological diseases or abdominal surgery;
• Cardiovascular diseases, cancer, liver or kidney malfunction, disease with a life expectancy shorter than 5 years;
• Abuse of products; alcohol and 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 3 months prior to the start of the study;
• Intensive exercise training more than three hours a week;
• Use of any medication that influences glucose or fat metabolism and inflammation (i.e. NSAIDs);
• Regular use of laxation products;
• Use of antibiotics in the last three months (antibiotics use can alter substantially the gut microbiota composition).
• Follow a vegetarian diet.
• Metal objects such as implants present in the body (e.g. electronic implants, pacemakers, metal fragments in the eyes, skin or body)
• The use of permanent make-up (eyeliners, eyebrows) or tattoos on the head, shoulders, breast or neck
• Claustrophobia