As far as I can tell, there are only two adult demographics in the U.S. in which the majority are of normal weight: college students 18 to 25, and military. This is discounting professional athletes of course.
Every other group of adults has a clear majority which are overweight or obese. This even includes young adults just entering the job market in their mid 20's. The percentage of young adults under 30 who are seriously overweight is alarming.
Just the other day, I saw a college aged gal at the cafe. She had two large bags of takeout, which I assumed were for 2 or 3 people. She at it all herself! A large salad, a large sandwich, two rolls, and a large drink.