Weight gain does not normally occur after gallbladder surgery, although several possibilities arise as to why this might occur in individual instances. The most plausible one would be the renewed ability to indulge in foods that were avoided because they produced pain from gallstones. Typically, foods that bring on gallbladder pain are the rich, fatty ones, precisely those that are rich in calories. Other conceivable but very remote possibilities include falling out of an exercise routine following surgery, or remaining off of cigarettes that were cut out in anticipation of surgery.