warpedpig

I'm not sure about Pakua but for Traditional Karate the average is about 5 years to attain a black belt. 2-3 years is McDojoland.

I would advise you to pay a visit to someone who can physically examine your back and provide you with a professional diagnosis - namely your doctor.

Any exercise which raises your heart rate into the aerobic zone for an extended period of time is effective for losing weight. I'm pretty sure that if you swim as fast as you can for at least 20 minutes, you will both feel the effect and see the results. I grew up in Mission Viejo, CA, one of the world's 'hotbeds' of competitive swimming and diving (Greg Louganis trained there), and some of the best conditioned athletes I've ever known were swimmers and water polo players.