--certainly, both gabapentin (Neurontin) and pregabalin (Lyrica) are associated with weight gain, and edema (water retention) if a well-documented side effect of both, but most of the anti-seizure drugs also seem to be associated with a carb-craving effect. People's appetite's seem to increase as if they are getting ready for a hibernation state--it's been speculated that the centralnervous system suppression of such drugs may be part of that mechanism.

In the end, you really have to be aware of this and watch what you eat.