If your goal is weightloss, hopefully with the main motivation of having a healthy weight, then this is what I would suggest to you:
Avoid anything fried from your sushi-place. Say goodbye to tempura.
Eat seewead salad as an appetizer. It will fill you up and supply you with great nutrients. Those salads with a little slice of cucumber and tomatoe really don't cut it.
About your sushi rolls: ask for brown rice only, so you feel more filled up, and it is just as tasty if not tastier than white rice.
Sashimi is probably your best bet, since the fish/carb ratio is a bit more favorable than with the rolls.
Make sure that if you get rolls with rice (pls make sure it is brown rice) then pick a place that doesn't put a huge amount of rice in the rolls. If they do it, go to another place. If you have no choice, then ask them to lower the amt of rice used per roll.
Good luck!!!