It's hard to say without seeing you. Us man-sized men still come in various shapes and sizes.
For me, I find it's easiest to conceal a fullsize handgun with a holster that doesn't ride too high. I'm well padded around the middle, but I have no butt or hips to speak of, so I need as much barrel as possible pressing against my butt-cheek to push the butt of the gun up tight against my side. A holster that rides too high permits the butt of the gun to sag outward, which is not only hard to conceal, but uncomfortable as well.
I prefer a holster with a good FBI rake that holds the triggerguard level with my belt; Some IWB holsters can comfortably conceal my 1911 if the triggerguard is behind my belt. If my holster rides at the correct level on my belt, I find that My 5" Springfield 1911 is easier to conceal than my Colt Commander or my wife's Officer's ACP.
I'd love to tell you that you need to get the same holsters that I prefer, but what works well for me may not work well for you. All I can recommend is that you try several holsters until you find one that works for you. (Which explains why so many of us have boxes and drawers full of holsters!)
I guess that at 6'3" and 295 lbs. I would qualify as one of the "fat guys".
I have had good success with Fobus paddle holsters. I have left handed models for my Glock 17, Glock 26, and Sistema 1927 (1911A1) as well as the double mag paddles for both 9mm and .45 as well. Of course the 26 is the easiest to conceal, but all three pistols ride up high an dclose to the body.
I know that some people think that it is an abomination to put a 1911 in a "plastic" holster, but beauty is what beauty does!
At 6'3 320, I'll chime in. For me,,,,I'm rather stocky for someone that is 6'3", that contributes more than anything to my weight,,,also, it makes finding concealment garments a little tough too. Generally it is tough finding the big stuff in tall sizes,,,,as I'm sure some of you have found out.
I generally carry IWB,,,,but I have to have a good quality belt to keep things under control. I tried using a pack,,,,but that sucks,,,,too slow and I don't care for carrying cocked and locked in a pack with a velcro holster holding the gun in place. A shoulder rig doesn't work, cause I can't stand having a jacket on all the time.
I though about using a regular duty holster, but it seems like I print a lot worse with it. Right now I'm using a Galco and it is OK, I'm going to step up to a custom soon, but for now I'm able to conceal my Para P14-45 with little to no trouble.
In fact, I regularly go to a local grocery store while carrying and they almost always have a polic officer stationed,,,,,he's never noticed,,,,or never said anything so I'm happy.
At 5'10" and 280 lbs., I find that the Bade Tech forward rake rig works well for all around assesibility and comfort. I have noticed over the years that if the holster isn't comfortable, you won't wear it.
I also wholeheartedly subscribe to the theory of having the gun in the same place, every time as there is too much going on during the "heat" to remember where your gun is. I think it's best for that problem to be resolved by habit and instinct engrained through thousands of dry fire draws from the same location.