Ive heard it said that the growth hormones in beef could have a hand in kids being larger than they were in the 60's and earlier. Who knows? Could be something to it.
Not only do we super-size our meals and have buffets galore here in America compared to Europe - but we have those sweeteners that mess us up - not to mention computers that won't release us so we can exercise! Thus, no lean machines! I admit - I'm guilty too!
And - You're absolutely right - they put growth hormones for animals to fatten them up for the market - and guess what! We are fattened up too! Have you seen the commerical about choosing chickens that have not been treated with growth hormones? I recently found out soy and broccoli makes you fat too! And - I love broccoli!
Bottom line though is the best exercise - Think Thin! What would a Thin person eat? And would they eat as much as I have on my plate right now...?
I suspect it is hormones, because diet overall is certainly not better than even 20 years ago, certainly not in things that help growth.