People that are more resistant to the effects of slin will start to accumulate fat in the abdomen area. When you first gain fat there it starts around your internal organs, which can make the abdomen protrude. Then you'll start gaining it sub Q, giving you a gut. Some people get it worse than others. It's basically a combo of being insulin resistant, having an androgenic body fat distribution, using highly androgenic AAS, and slin.
I don't get that problem because I have an estrogenic body fat distribution. I hold fat in my legs.