I have an abnormal EKG, mine is a negative T-Wave. If you look at a heart rhythm on an EKG, there is a small bump, then a line that goes up, then down, then returns to the level from which it started, then another bump. These are the P-Wave, QRS Complex, and T-Wave. If the T-Wave is negative, goes below the base line, this can be a sign of problems. Some children and adolescents have negative T-Waves normally, as do some adult athletes, and a very small percentage of adults have it normally too. I've been told to carry a copy of an old EKG lest someone, like at the E.R. thinks my negative T-Wave is abnormal. I have EKGs from 20 years ago that show it. But someone that had a positive T-Wave on one EKG, and it's negative on the next (adults), this warrants additional testing.
Ask your doctor what the abnormality is in the EKG and what he/she is looking for by requesting the Echo (I trust your doctor didn't mean an Echo/Stress test). Losing weight is laudable, but be sure you find out why the doctor feels your EKG was abnormal.