Hi, I am 5’8”, 183# in fairly good shape and am trying to trim up. I have worked out twice a week in the past, but have decided to do more cardio to lose weight. I started a cycling class, high intensity for 45 minutes. I have went 3 times. My third class was Monday. I ate 1970 calories for the day, went to class, and the next day had a weight gain of 2 pounds. Why????