Thought it would be good to post links here on Mods that allow weight gain or just increase the weight of the character in those games.
I’d like to start with Skyrim. I used to play this a lot and even ran a thread for Bodyslide mods.
So Bodyslide is a tool for setting the default high and low weights for your characters in Skyrim. It can technically be used on any gender, but really 99.9% of all of the mods are for female characters.
I highly recommend you check out the Bodyslide List here: http://www.loverslab.com/topic/16350-bodyslide-armor-and-clothes-list-v2/
And of course the main mod: http://www.nexusmods.com/skyrim/mods/49015/?
You see every armor in the game whether original or modded in needs counterpart bodyslide files in order to be adjusted. However once made you can apply a preset. My first serious preset was called Ai to Amy. Thats because I set the low weight proportions similar to Ai Shinozaki and high weight to Amy Villainous. You can’t get to extreme in size as the armor and bodies geometry starts breaking up.
Once you have a decent upper size you might then want to install a mod that increases your characters weight or others.
One would be Porked Up http://www.nexusmods.com/skyrim/mods/23448/? or this add-on for realistic needs http://www.loverslab.com/topic/17160-weight-change-realistic-needs-and-diseases/
For other characters try the weight alteration spell http://www.nexusmods.com/skyrim/mods/50625/?
A mild example attached.
Now the good news is I can see this all being ported to Fallout 4. So if that’s your bag, get bodyslide for that.