It really depends on how hot it is outside. I'm not fat, but I do think that 78° is quite warm and pretty uncomfortable. However, if the AC was set to 78, that means it was hotter than that outside. If it's 90° outside, then 78 is fine. I know it's at my AC that low either because I like to save money. I can deal with a little bit of heat.  It's all relative.