Lifting is *not* risk-free for J-pouchers , but folks may judge it worth the risk if lifting is important to them. The usual suggestion is to wait six weeks after abdominal surgery to resume “unrestricted” lifting. A lifting belt can’t harm the pouch, and might help prevent some (but certainly not all) potential injuries.
The most likely lifting injuries related to J-pouch surgery are probably incisional hernias and pouch prolapse. Girlunky’s lower weight/higher rep transitional strategy probably reduces the risk substantially, but some risk persists over the long term. One approach could be to adopt that strategy permanently instead of transitionally. A J-pouch isn’t original equipment - it’s more like a clever Rube Goldberg invention, with some vulnerable attachment points.