I saw a US class photo from 2017. the percent of fat students was like 70%! Then I saw another class photo from 1980. Almost everyone, like 90%, was so slim and trim! I had my theories but now I just have one. First I will list what I used to think:
1. The computer age took most the available movement time (like going to the store versus online shopping, etc.) causing the weight gain, starting about the early 1990's.
2. Food ingredients changed in the early 1990's. Fat was replaced by more calorie dense sugar.
3. There is a virus causing it.
4. Portion size increased.
But here is my current theory and it's so simple: In the US today, and starting in the early 1990's, the calories consumed per weight of the average person increased greatly and the energy expended decreased moderately.
Anyone know differently?