In this placebo controlled, double-blind, randomized crossover study the investigators will investigate in overweight/obese healthy male volunteers whether inulin administration will increase intestinal SCFA production, thereby investigating whether this will lead to acute metabolic effects.

Gut microbiota is being increasingly recognized as an important factor in fat distribution, insulin sensitivity and glucose and lipid metabolism. Accordingly, the intestinal microbiota could play an important role in the development of obesity and type 2 diabetes mellitus. The role of gut-derived short-chain fatty acids (SCFA), the formation of which is enhanced by microbial fermentation of fibre, is still controversial. At the present time, our understanding of the effects of SCFA on human metabolism (in gut or systemically) is still limited. The investigators hypothesize that the ingested prebiotic inulin is fermented into SCFA and these SCFA have metabolic effects.

Inclusion Criteria:

• Overweight, obese men

Exclusion Criteria:

• athletes
• diabetes mellitus