It is possible to gain weight after stopping Topamax (topiramate), as it is known to cause weight loss as a side effect in some people. However, weight gain is not a commonly reported side effect of stopping Topamax. The effect of stopping Topamax on weight may also depend on individual factors such as diet, exercise, and other health conditions. If you are concerned about weight gain after stopping Topamax, it is best to speak with your healthcare provider.