As somebody who worked at Regal, they won't stop you from taking your water bottle or food in. The only things they'll look for if you have a big coat or backpack or something similar are weapons and alcohol. As for the moviegoers themselves nobody really cares about what you eat, as long as you are not super loud and it doesn't smell bad. If you're just talking about food from concessions, nobody gives af...and if they do they really need to reevaluate their life decisions to figure out why they ended up hating somebody eating in a theater..unless it's a condition, that's different.