All indications are that Americans are fatter than ever, but I wish this poll included height as well, for more context. Even though BMI (height + weight) is imperfect, I think it's still more descriptive than just weight alone. Also, the average height of populations changes over time, so naturally their weight will also increase, but that doesn't necessarily mean it's an unhealthy increase.

According to this Time article, American heights increased in previous decades but pretty much stalled out: https://time.com/4423803/how-tall-100-years-height/ So I guess the results are pretty much the same even without the height info.