I have worked in a bike shop and for about 10 years had a little bike shop in my detached garage. I explain that because it allowed me to talk with a whole lot of people about ebikes. I also built or sold ebikes to several customers at their request.
I suspect that at least some of the weight loss may be because the ebike rider wasn't riding at all so riding an ebike allowed them to get exercise. Same with some seniors and folks who wanted to commute but had big hills or didn't commute because it was too far or too sweaty.