system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are everyone in '50s & '60s photos so thin?
gpt
In all seriousness, because people are fatter now.

Children moved more in school, and we're much less likely to be driven to school, more likely to walk or ride a bicycle to school.  Play was much more likely to be outside - no video games, no computers, no mobile devices.  Oh, yeah, talking with friends?  You gotta walk or bike over to their house.  Children don't use the phone much in the 50's and 60's.

Adults got much more exercise, too.  Many more professions were physical, like manufacturing and such.  But even daily life was much more physically demanding.  No dishwashers, most food preparation was done by actual cooking, less by take-out, or pre-made stuff like Hot Pockets, or frozen pizza.  Even activities like typing were more calorie-burning - modern keyboards require much less human energy than manual typewriters, especially if you had to punch each keystroke through three or four layers of carbon paper.  No remote control for the TV set.

And perhaps a little more somberly, we don't really realize how much easier it is to be in poverty today, in 2015, compared to the 1950's and 1960's.  The biggest nutritional problem for the bottom 20% in the USA was finding enough food.  Period.  People were medically underweight because of malnutrition.  They literally were so poor, that the couldn't buy enough *rice and beans* to get to a healthy weight.  Today's main nutritional problem for the poor is obesity.  That's how great our society has been the last 60 years.