Low Blood Pressure And Weight Gain

I have been on blood pressure medicine for years. I've been on many diets and it's hard to loose weight no matter what I try. My sister had me use her watch that checks your pulse rate. My pulse was between 63 and 65 (I tried it more than once). That was my resting pulse rate. She thought that was pretty low. We checked my dad's and his was around 75. I'm 49. I go to the gym 3 times a week. My Dad is 79 and has arthritis and doesn't walk much. No matter what diet I try I can't loose weight. I thought after 7 months at the gym I would be loosing weight. After seeing my pulse I remembered about the blood pressure medicine I'm on. I take 50 miliigrams of Atenolol and 20 milligrams of Enalapril every day. Atenolol I remember reading, is a beta blocker and it slows your heart rate down. Is it possible the Atenolol is why my heart rate is so low and actually keeping me from loosing weight?

Your feed back is much appreciated!