Why were people so thin in the 1950s-1970s?

This is a multi-prong issue.

The culture was different. It was a culture where one person worked and the mother stayed home so people had more free time to exercise. It was also a time when there wasn’t a lot of junk food or candy. And people were encouraged to get exercise in various ways, whether through sports, hiking, or another method. In the 1970s my elementary school was 1 mile away and I walked to school every day through back lots.

However over time candy and junk food got cheaper, and easier to get. The cost of living went up so both parents had to get a job, leaving the kids to take care of themselves for part of the day. Kids don’t like to cook, they like to play, so they eat what is fast and go back to playing. Video games and TV eventually got more common leading to less exercise.

The number of vaccines a child gets also increased a lot over the years in the US. And glyphosate and artificial sweeteners were used more and more. We now have studies that show glyphosate/Round Up is in the food system in the US as well as in Europe. In the US you cannot grow food for people that was sprayed with glyphosate, but you can import it. US gets much of its food from Mexico where the pesticide regulations are very lax and just not enforced most of the time.

Phthalates are also used in plastics and during this time plastic use shot up. Phthalates are known endocrine disruptors and mess with your hormones. Soy is also an endocrine disruptor, it acts just like estrogen in your body, the body doesn’t know the difference.

Personal exemptions also dropped like a rock, as the cost of living increased.

Chronic diseases also went up. Vaccines are linked to a higher incidence of asthma and allergies. Inflammatory diseases have also gone up, asthma and allergies and diabetes are all inflammatory diseases and some mental conditions, like behavioral problems, are thought to be inflammatory diseases as well.

Stress has also gone up as the cost of living has risen in the US and incomes have not kept pace with inflation. Even the inflation number has been higher than COL since around 2000. But companies don’t give raises based on inflation, they use the government COL.

Conclusion

There’s not just one issue that can be blamed for being overweight. It’s several issues.