Earlier quoted context omitted.
I am really surprised about the sharp increase in body size by age in the USA. I have just anecdotal experience here in Europe, but I know for a fact that all the females in my family have kept the same size since they were 16-18 years old. That’s also my experience with the male side of the family.
Most adults in the US become physically inactive after they leave school/collage and move to an area where they have to drive everywhere, while sitting in an office the rest of the day. While I'm well aware weight gain requires over consumption, I feel there is an under appreciated importance on being somewhat mobile rather than sitting/laying down for 23 hours a day
For women, it's very common to consume sugary coffee flavored drinks and this behavior is glamorized on social media.
For men, the problem is worse.