I'm sure this is completely unscientific but it based on personal experience. I had a valve replacement a couple of years ago, also had fast AF for a few weeks before the op and slower AF for a few months afterwards. In that period, I lost nearly a stone in weight. This was just enough to get me at target BMI and I dropped a dress size (new clothes)! I had a healthy appetite throughout,the only difference being that I gave up alcohol for about 3 months. The only additional medication that I had was Bisoprolol, which actually makes some people put on weight. Now my AF has come back and the weight is dropping off again. I still eat the same amount and have a glass of wine about 4 times a week.
Mu cardiologist says that a faster than normal heart rate is like someone exercising all the time. So is the AF affecting my metabolism?