The present invention relates to dietary fiber compositions that can provide an increased level of acetate in the distal colon. Increase levels of acetate (or other short chain fatty acids; SCFA's) in the distal part of the colon is believed to be beneficial in the treatment of various diseases or conditions, such as being overweight or obese. To accomplish this using dietary intervention, which is clearly the preferred (first-line) option for the treatment and/or prevention of obesity (and related disorders), has been a challenge. It was now surprisingly found that combinations of an inulin-type fructan and resistant starch can be orally consumed to substantially increase the level of acetate in the distal part of the colon in human subjects. Hence, the present invention provides dietary fiber products comprising combinations of an inulin-type fructan and resistant starch, alimentary products comprising such dietary fiber compositions, as well as the use of the dietary fiber compositions or the products containing them in the treatment or prevention of a medical or non-medical condition, such as obesity or being overweight.