Polydextrose (PDX) and lactitol enhance satiety and may influence blood glucose and lipid levels. Furthermore, low levels of colonic Bacteroidetes are associated with increased BMI. Wistar rats were acclimatized with a high fat diet for two weeks before the intervention. Rats were orally administered with saline containing Bacteroides thetaiotaomicron (1010 bact/rat/d) with or without addition of PDX or lactitol (2 g/rat/d) (Danisco USA Inc.), or saline alone for 8 days. Post-prandial blood samples were collected for the determination of levels of triglycerides (TG), glucose, insulin and gastrointestinal peptides. At the end of the trial, caecal digesta samples for short chain fatty acid (SCFA) and faecal samples for dry matter and heat value analysis were collected. B. thetaiotaomicron supplementation alone did not have any effect on body weight gain, but when it was administered together with lactitol or PDX, there was a significant decline in the mean body weight. TG was decreased by the combination of B. thetaiotaomicron and lactitol or B. thetaiotaomicron and PDX but there were no changes in TG in rats supplemented with B. thetaiotaomicron alone. Both lactitol and PDX in combination with B. thetaiotaomicron significantly decreased the caecal SCFA concentration and the faecal dry matter. The feacal heat value was increased in B. thetaiotaomicron-fed rats. In conclusion, B. thetaiotaomicron has only a minor effect on weight whereas polydextrose and lactitol may be useful in weight management and attenuating post-prandial triglyceridemia