Immediately after an operation on the intestines, most patients don't have a regular appetite for a few weeks. It is normal to feel full after smaller meals and not be as hungry as usual. The appetite will return after a few weeks. In the meantime, the most important thing is to stay well hydrated by taking in enough fluids. Eating a bland diet is helpful but not required.
For patients who have difficulty with bloating or bowel obstructions, limiting the amount of ruffage and undigestable fiber is helpful after bowel surgery. This means limiting certain foods like raw salads, uncooked vegetables, and things like that. Overall, a healthy, balanced diet is best after most gastrointestinal operations.