Heart Rate

So to start I'm pretty overweight. I lost 12 pounds this month since starting my journey to be healthy. I started eating very low everything. Mostly eating salads or green vegetables sometimes with a baked chicken breast, yogurt in the a.m, maybe pickles to edge away the hungry feeling, nuts, fruits, and water. My heart rate was normal before 60-70 at resting now it's in the 50's. Is this because of not eating much? Or is there something more to be concerned with? I plan on making an appointment tomorrow, but am still curious. Having a bit of health anxiety, and anxiety in general doesn't help either. Any replies would be very welcomed and thank you in advance.