When looking to buy a suit, you should notice the kind of vents the suit has. The vents are often forgotten but can either help out your physique or hurt it. They are also a signal for how dressy a suit is. Don't over look the vents. The three kinds of vents are: Center Vent, Side Vents and No Vent.
Center Vent - This is the cut up the middle of the jacket. It is typically found on the more casual blazer and suits. It is a very American cut, but offers little benefit to your figure. Center vents are the most common vent, so every closet will have them. Despite the commonality, they offer no benefit to the physique of the wearer. Just make sure that when the jacket is on that the center vent is closed. An open vent means that the jacket does not fit right.
Side Vents - are found on either side of the back panel of the jacket. Side vents offer a great range of motion and typically found on more modern suits. The English prefer the side vents as they are considered more proper and formal. Side vents also benefit most men's physique. Men with extra girth should always opt for side vents as the two vertical lines in the back of the suit are slimming. Side vents also allow the back of the suit to lay flat, no matter the body type. I always try to buy my full suits with side vents.
No Vent or Ventless - Jackets with no vents provide a very slimming shape to the wearer, but limit the range of motion. The look when standing is clean and sleek. It is a formal look, often used in Tuxedos. If you don't mind the restricted movement, then a ventless jacket can help any man look slimmer, especially a hefty man. That being said, I will always opt for the side vents as the range of motion is an important factor to me.
Remember to check the vents before buying your next suit.