Topamax was put on the market as an anti-seizure medication. It basically helps deaden nerve cells. One of the side effects is that it helps people with migraines. It's not even typically prescribed for people with mild migraines either because of the side effects. And it has some pretty bad ones, including being so "fuzzy headed" you have a hard time carrying on a conversation. It's now being prescribed for people with severe ADHD because it slows them down so much. Other typical side effects include anxiety, depression, and and dizziness.
Prescribing it or taking it for weight loss is irresponsible imo.