I don't lose or gain weight much because of riding, electric or non, and I'm into my 8th decade of riding. I do gain 5-8 pounds each winter because I do ride my AirDyne then, less than I ride my other bikes the rest of the year. A tiny part of that gain is due to non-optimal holiday eating.
On the other hand, I have lost about 10-15 pounds this year because I have not eaten at a restaurant since mid-March -and even though I have also ridden less since then. A tiny part of this gain is due to not getting a haircut since then either. Stay healthy and safe everyone.