A slidebelt ($28). I recently bought one and it's superior to any belt I've ever owned. It instantly tightens if I want to run, and with only slightly less effort loosens. It's exactly the right tightness, no holes. If you're losing weight and the belt is sticking out too far, just take it out of the buckle, cut, replace it within the buckle. And since the makers don't have to worry about variable belt lengths, they can make it up for it by offering a variety of buckle designs and belt colors.

It is Correctly Designed and a joy to use.

http://www.ebay.com/itm/Original-SlideBelts-Mens-Genuine-Lea...