Maybe try having it in 2 or 3 separate portions then it doesn't hit the tum all at once - say some sprinkled on yoghurt, some as porridge and some as a gallette or a muffin?
It does swell up in the stomach, which of course is why it makes you feel full, as well as being lots of fibre. i have to admit I really like the oatbran now, much prefer it to anything wheat based like bread or cakes ( really I do!)