My country does follow the trend to oversized portions as well and I suspect we have a similiar amount of thick people around like in the States. I myself am a good eater and cant free myself from guilt.
but with the present environmental conciencse emerging stronger in my country, I have asked myself a lot of questions and am daily faced in the news with a lot of facts. For example huge cow herds, who eat half of the countries plant production to provide meal for monster burgers, which are only eaten half and then thrown away, while in others places on the world people die from starvation. I cant stand that with a rational mind that makes me feel bad.
my gf and me are trieing to live a bit more ecologically and we try to buy food in rational sizes. So far it has played out very well for us, I am not hungry in the evenings and I pay a lot less for food. We have cut our food spendings per month for almost 200 Euro.