Learning! It was easier to be skinny in the 80's than it is today
Here's a big piece of news! New research has shown that people following the exact same diet and exercise regimens in the 80's will have a BMI 10% less than a person today (okay, it actually compared to people in 2006, because of available data). The research measured calories, macronutrients, age, and exercise habits.
Wow! Possible explanations include increased exposure to chemicals and hormones that may be weight gain-inducing, an increase in prescription drugs that cause weight gain, as well as possible changes to some of the gut bacteria that impacts weight. (In a high-five to vegetarians, it's possible this is impacted by increased meat consumption, being that meat contains loads of growth hormones and junk these days.)
Maybe we should be a little less judgey of people who don't have perfect bodies then, eh?