Altering the waist size of kilts is yet another reason why it's nice to have a kilt without belt loops, and pleated to the line (because you can move the belt loops but if the kilt is pleated to the tartan you end up with the sett off-centre).

Pipe band kilts get altered the most and were I getting kilts for a band they would be pleated to the line and without loops.

I lost 45 pounds a couple years ago and I had little trouble moving the buckle on my kilt. Singular because I only moved one buckle, the one on the wearer's right. On the other side I moved the strap but left the buckle where it was.