The late Mr. Ferre shows how a larger man can wear his pants at his waist WITH a vest and create a very slimming effect.
Again, the "rules" don't work for everyone but they can usually be slightly tweaked and work more often than not.
If you are taller, check out old photos of Gary Cooper, Jimmy Stewart or Gregory Peck - all tall and still wearing their pants at their waist (with very successful results)