I do not believe those men that claim they can go on the road for a week with little more than a carry-on. When I was living in hotels three weeks out of four years ago, I wanted three suits and two pairs of shoes for five days in addition to whatever I was wearing to go to and fro. Not to mention the travel umbrella, workout stuff and power adapters. That meant a 70 pound (32 kg) bag, and though I might need a porter from time to time I never wanted for clothes.
I tried travelling light recently, on the assumption that I had only four days in cities and would not need to be very formal for wandering around the rest of the time. Expecting weather in the 70s (20s C), I wore a shirt jacket for the flights, and packed a blazer and the ten ounce (300 gram) suit in the photo. Unfortunately, the weather was like August, or so the locals told us. Alternating two jackets meant I was wearing said middleweight suit on a sweltering day in Naples when my inability to find a taxi meant several sweaty miles of walking. Had I packed a larger bag, I would have had space for a linen suit that would have been a lifesaver.
Upon my return, the pinstripes were off for a most necessary cleaning. Travelling light is over-rated.