These days most gents use a belt as a method of supporting their suit trousers, which is unfortunate. My understanding is that English suits weren't traditionally supported by belts. Rumour has it that the Duke of Windsor went to an American tailor to have his suit trousers with belt loops made because his London based tailor refused to. Wonder why? There are many reasons not to wear a belt with a suit: The visual flow from the jacket to the trousers is broken by the belt. The belt cuts the wearer of the suit into two. The line of the fitted suiting is disrupted by the belt buckle. A belt buckle creates a lump under a waistcoat on a 3-piece suiting. Trousers will sag during the day with a belt and need to be pulled up or and adjusted. Problem number five can be solved by using braces, the remaining four problems can be resolved with side adjusters. It was common in the 1950's for English tailors to make trousers with an adjustable waistband system to substitute the braces. And there are a number of different types of waistband adjusters available. So when commissioning a suit next time, think of the side adjusters and or braces solution. No belt loops on suitings. Below Mr. Martin and Sinatra in single breasted well cut suitings, no need for supporting the trousers with belts, as these trousers are bespoke. The visual flow of the suiting is not disturbed by a belt or belt buckle. Very clean and neat. Below side adjusters on Mr. Bond's English cut suit, no belt disrupting the visual flow. The three piece suiting is in one. A bespoke Ambrosi trousers so well fitted needs no side adjusters Below different types of side adjusters Pictures sourced from Style Forum and A Suitable Wardrobe