Over the past week I have gained 3.2 lb, so I am freaking out; however, I have been working out twice a week with a trainer, and have lost 2.2% body fat over the past week as well. I did not realize miscle weighs that much more than fat.....is this normal to gain weight with weight training???

100% yes! Muscle is definitely heavier. You will lose inches and lower your body fat but actual weight will probably go up. It's not a bad thing at all!!! Congrats!

Folks are sometimes confused by the statement that muscle is heavier than fat. A pound is a pound. The key is that muscle is heavier than fat *by volume*. So a pound of muscle has considerably less volume than a pound of fat. That's why we often see people say they are not losing weight but they are losing inches. Smaller volume and relatively heavier muscle replacing larger volume and relatively lighter fat. Great job! Keep it up!!

It could also be water weight. I struggle with that as well and I also weight train and someone had mentioned the water thing. Although I drink at least 64 oz of fluid a day sometimes half is on water. So I'm trying to have at least 64 to 100 oz of just water and so far this week has been a good week with weight loss. Good luck!