i just joined my local Y-- and i love it. they have a great pool here for laps and my membership includes all the classes i want, and personal training.. i have been lap swimming for over an hour a day-- its great!

I've been to Curves (it's called Body here in Tokyo) for a 1-day trial and I have to say it really wasn't much of a workout. If you're aiming for weight loss and shaping up I'd say go for YMCA with all the different classes you can take!

I'm not sure exactly what kind of classes YMCA has, but as an idea you can take yoga/pilates for stretch and building core muscle, step aerobics for cardio, and kickboxing for cardio as well as some muscle toning. If they have any group weight training lessons that you can work into your workout program then you'd be all set!