Who or what is to blame for obesity in modern world?

To begin with, I think that the main thing to blame for it are our primitive instincts. This is the reason why we like sugar so much in the first place. However, the food companies started exploiting it, using sugar as a cheap additive used to increase the taste of the product, which will result in customers choosing that maker again, because of how nice it tasted and satisfied our brain. Still, we are also to blame. We get to choose what we eat and falling thousands of times for the same marketting trick each year, we are responsible for our bad diet habits. I don't mean that we should only buy special, expensive and eco-firendly products, but we should study the table of contents carefully and sometimes spend something extra if it is worth it.