If you were healthy and at a good weight when you were twenty five, there’s almost never a good reason to be significantly heavier than that.
People like to tell themselves they’ve added muscle over the years, about which two things: First, come on, that’s usually not the case. Second, to the extent that people do add muscle as they age, it’s often to support their bones, ligaments, and tendons to help deal with the more likely source of increased weight, fat. So even in that case, the extra muscle isn’t going to help you run faster.
As runners, we already live in ways contrary to accepted beliefs on what aging is supposed to be like. Why not take that attitude toward weight as well?