We need to consider that endocrine disruptors (the plastics mentioned) may interfere with the systems that control feeding behavior such as leptin and ghrelin.
But when you completely upend society in a generation, changing a thousand variables at once, I do not personally feel comfortable saying "far more likely" about any particular cause for any particular societal outcome.
- Plastics in EVERYTHING throw off hormone balances, including both metabolisms and... other things hormones affect. It's not just BPA.
- Dramatically different ages and rates of childbearing. Both lifestyle and hormones again.
- Pornography has completely changed how many men (and some women) interact with society. Lifestyle and... hormones.
- What percent of Americans are on some form of chemical antidepressant? A lot.
I'm sure there are dozens of other plausible drivers, and the answer isn't any single one.