There was a 2007 study of over 12,000 people followed for 32 years. It showed that obesity is almost contagious, that people were most likely to become obese when a friend became obese, especially a close friend. If a friend of your becomes obese you are 57% more likely to be obese, and if that is a very close friend, your risk almost triples. And proximity does not seem to matter: the influence of the friend remained even if the friend was hundreds of miles away.
Beneath our own individual biologies and mind-states, we live in a society and culture that fundamentally determines how we live. In modern society, we live in a situation where high-calorie food is everywhere and cheap, it is easy to be inactive and it is sadly common to be alone. When over 60% of people in our society are overweight perhaps it is our culture that is the cause of our obesity and not necessarily just the choices of individuals. The human brain and body are wired to survive in a completely different environment to the modern day. We evolved to survive in the short term and in small tribes in an environment which had little food and required a lot of activity. Now we have the complete opposite, and it is no wonder so many are overweight.
So, are we wrong as individuals or is the situation we are in just not right for us? I am not suggesting we go back to the stone age, but rather how can we adapt our current culture and political systems to work with us, not against us? Many now are aware of this and trying to figure it out but in the meantime just remember that the influences to what decisions you make go profoundly beyond just you as an individual. Change what you can as an individual and if needed work with others to change the situation we are all in.