This belt is designed to fit around your waist snuggly. The elastic is used to help create tension on your holster to help press the gun into your body. Try adjusting your belt a little bit tighter and see if it helps.
Adjust your belt slider one piece of elastic at a time. The belts are universally sized, so they can fit a variety of waists. Once you have the belt adjusted, there is no need to change it.