resistance training and plateau

I had gastric bypass on Dec 2 2009 and I have done really well.  I managed to lose 100 pounds by July.  Who believed that was possible in 7 months!  Since then, the weight loss has really slowed.  I have waivered back on forth on the same 5 pounds since the middle of August.  I am getting really discouraged.  I started working out in January with a trainer.  She is great.  I go 2 times a week to work with her and an additional 2 times to do cardio on my own.  I am buring incredible amounts of calories in the workouts, but the weight just won't come off.  Does anyone have ideas?  I am at my whits end.  Trying so hard not to let this get me down.

My 2 cents is not to go by the scale. Is your body changing ? After a huge loss , you have lost a lot of muscle along with fat. When you first start strength traing it's not hard to put a few pounds of muscle on while still losing some fat. The net result may not be showing on the scale but it may be changing your body composition. Also as you do strength training your muscle break down and repair themselves which causes some water weight to be withheld.

Also, if you aren't tracking your food, you need to be. It's really common for people to eat more to make up for working out more and not even realize it. This is why studies often show that exercise alone doesn't lead to weight loss.