HELP! Gaining!!!
Well, are you sure you're eating exactly the same? Maybe your portion sizes increased without you realizing it. How long have you been gaining? Is it a temporary increase that could just be fluid retention? Did you have RNY? The malabsorbtion of calories is less over time as your body grows more intestinal villi to compensate for the bypass. So you could be eating exactly the same but absorbing differently. Also, if you've been doing exactly the same exercise routine for months, your body will become more efficient at doing it and you will burn less calories doing the same amount of work.
Keep in mind that you won't regain the ability to absorb certain vitamins and minerals, just calories. Stick to taking your vitamins, eat a high-protein, low-carb diet, and watch out for 'sneaky' carbs. Avoid things that have been made artificially low-fat---when they take out the fat, guess what they replace it with? (Carbs!)