Clothing belt adjustment systems are configured for wearing around a user's body such as around the waist. The belt adjustment system includes a belt and a buckle wherein the belt can be looped and secured to the buckle to secure the belt around a user's waist or other portion of the body. The buckle has a body with a thin side profile that is not overly bulky such that it can comfortably fit over the button region of a wearer's pants. The buckle advantageously includes one or more threaded retainer members, such as threaded screws, that secure one portion of the buckle to another portion of the buckle.