I wonder if the authors of the study considered Non-exercise activity thermogenesis (NEAT). This is the energy expended for everything we do that is not sleeping, eating or sports-like exercise. It ranges from the energy expended walking to work, typing, performing yard work, undertaking agricultural tasks and fidgeting.<p>If they only selected white-collar / desk workers for the study, then it's possible that people expended more NEAT back then in their office environment. Just looking at movies from the 80s, you definitely see more physically active offices than what you see today. People walking around to pass memos, papers, attend physical meetings, etc in the 80s has been replaced with people sitting at a computer to send emails, chat messages, meeting invites, etc.<p>Also,the nature of jobs people do today is a lot different. There was a study that showed US men's grip strength has been decreasing from generation to generation. No surprise given that the US economy has been changing from a manufacturing and agricultural based economy to a services one.<p>Here's an article mentioning the study - <a href="https://www.npr.org/sections/health-shots/2016/06/13/481590997/millennials-may-be-losing-their-grip" rel="nofollow">https://www.npr.org/sections/health-shots/2016/06/13/4815909...</a>
>>Americans are eating more meat than they were a few decades ago, and many animal products are treated with hormones and antibiotics in order to promote growth. All that meat might be changing gut bacteria in ways that are subtle, at first, but add up over time.<p>So people are eating differently. Doesn't everyone already know that the food you eat affects how easy or hard it is to stay a certain weight?<p>>> Americans are eating more meat than they were a few decades ago, and many animal products are treated with hormones and antibiotics in order to promote growth. All that meat might be changing gut bacteria in ways that are subtle, at first, but add up over time.<p>...you mean if the research is correct and if you're eating differently and taking prescription drugs that cause weight gain.
The articles guesses as to contributing factors:<p>> People are exposed to more chemicals that might be weight-gain inducing. Pesticides, flame retardants, and the substances in food packaging might all be altering our hormonal processes and tweaking the way our bodies put on and maintain weight.<p>> The use of prescription drugs has risen dramatically since the 1970s and ’80s. Prozac, the first blockbuster SSRI, came out in 1988. Antidepressants are now one of the most commonly prescribed drugs in the U.S., and many of them have been linked to weight gain.<p>> Study authors think that the microbiomes of Americans might have somehow changed between the 1980s and now.
It was easier for me to be skinny in the 1980s: I was younger, and for the first half of those years ran a lot--at least a couple of marathons every year.<p>But, "A new study finds that people today who eat and exercise the same amount as people 20 years ago are still fatter." The 1980s were nearer 40 years ago than 20 years ago.