@MrsWinslow - Lipotropic drugs for weight loss are things like ephedra, which was banned for causing serious illnesses. You are probably thinking of drugs like orlistat (Alli over the counter) which seem to work differently from lipotropics. (I'm no expert, but what orlistat does is prevent the enzyme lipase from breaking down fat, which sounds different.)
I remember reading about these drugs that they make you get really sick if you eat a high-fat meal, so their biggest benefit might actually be the behavior modification aspect!
If you are trying to lose weight to get normal menstrual cycles going, make sure to look up the Newsweek article from a few years back about the fertility diet. It talks about what foods are helpful. (I remember that vegetable protein and whole milk dairy were both good and that white carbs were bad, but you should read the details for yourself.) Good luck with your baby dream!