I cannot speak from experience on this question, however, researching brings me to two different answers. Some gain weight after having their gall bladder removed, presumably, because they can now eat foods they wouldn't/couldn't have eaten before the surgery. Some report just the opposite, they have lost weight after having the gall bladder removed because they can now eat more "healthy" foods. I definitely would ask a physician about this and also check for any other "underlying" causes for weight gain or loss after the surgery.
There have not been any conclusive studies done on it; however, it does seem as if there have been a good deal of people who have gained weight after having their gall bladder removed? The best advice on what helped is to follow a sensible diet, watching those calories. Your doctor can advise you on the best type of diet that is based on your needs.
I have had a few friends that have had gall bladders removed and they all told me that they have gained weight after. After doing my homework I have found that the reason for the weight gain is that the gall bladder helps digest fats and without it, you don't digest fats as well so you gain weight. The only help that I can give you is to first check with your doctor, but start on a healthier diet and an exercise program. You may also want to try eating more salmon and taking bile salts that can be found in a pharmacy.