can't lose weight

i have been suffering from palpitations (extra beats),  and a bunch of other stuff but all the cardiac tests are normal.   i'm convinced it's because of my weight now,   i'm 5'10"  257 pounds, 30 yr old male.    what i dont get is that i was 245 pounds, then I started exercising again and my weight actually increases when i exercise!     i put in 45  minutes of very good cardio almost every day, with ia little weight lifting too.   Why do i gain weight when I start exercising?!     I also have (new) unexplained  bilateral perifphreal edema  in my lower legs,  but a normal BNP, Stress test,  Echo, CTA, Liver tests, thyroid...you name it....why oh why do i gain weight?    sometimes i wonder if its because i drink more water,   or because i'm more hungry and eat more when i workout every day, but still i don't know,   it seems odd.

[Douglas Bogart, MD]

Water will not cause weight gain with normal heart and kidney function.  You likely do consume more calories when you exercise.  You might consider the South Beach Diet and if you follow this you will loose weight.