Don't blame your trainer for poor results:

I recently turned down a prospective client who wanted to switch trainers.  She was unhappy with her current trainer, because after 6 months of training twice a week, she had not lost weight.  She did admit to shaving a few points off her blood pressure and cholesterol, but blamed her lack of weight loss on her trainer.  After some delicate questioning I learned that she did not work out on her own, and despite her trainer’s recommendation, she had not changed her eating habits at all.  I tried to be diplomatic, but she got angry when I suggested she stick with her trainer and listen to his advice to see a nutritionist and to work out additional days  

You may not want to hear it, but no matter what you do with a trainer, if you do not change your eating habits you are unlikely to lose any significant weight.  You also probably need to work out on your own, unless you can afford a trainer 6 days a week.  This is not new information, but it still seems we want easy fixes.  To lose weight, exercise alone will not do it, especially if it is only two or three days a week.  Exercise is the most important thing you can do to maintain weight loss, but you would need to do an incredible amount of exercise each day to lose weight from exercise alone. 

To lose weight and keep it off most people need nutritional help.  If you can afford it hire a Registered Dietician for some guidance. Make sure to check credentials; in most states anyone can call him or herself a nutritionist, but a RD must pass a national registration exam.  (This site will help you find a RD: http://www.eatright.org/programs/rdfinder/).   A less expensive option is Weight Watchers: (http://www.weightwatchers.com/index_v.aspx)

 This is one of the most effective weight loss programs for the long term.  Weight Watchers teaches you to eat right when you have lost the weight.  Most people find keeping weight off is as hard as losing it, so programs with liquid diets, lopsided nutrition or fake foods are ineffective in the long run.  With Weight Watchers you can chose to go to meetings where you will get guidance and support, or you can sign up for their online program.  If you have struggled with weight issues for years I also recommend Overeaters Anonymous (http://www.oa.org/) another effective organization that works on the buddy system to help you find your way.

Someday we will probably have magic pills for weight loss, but until then I am afraid a realistic diet combined with exercise is still the only way to get results.