To lose weight a female will need to eat about 1200 calories daily. The best diet is a high fibre, low fat diet with balanced amounts of carbohydrate and protein. Drinking 8 glasses of water daily, eating 5 portions of fruit and vegetables all constitute a healthy diet. If you can fit in 30 minutes of brisk walking daily then you should see weight loss of about 2 pounds per week. This is sustainable and healthy.
Ephedra has been banned due to numerous problems with safety so you will not be able to get it in the US. Your doctor may be able to prescribe orlistat (fat absorption mechanism) which can help with weight loss and encourage a low fat diet.