Yes obesity is a problem, and the factors that contribute to someone being obese are multiple and complex.
My eldest son has complex needs, including complex mental health needs. He lived in residential accommodation for people with complex needs for three years, and he now lives in supported accommodation. Many of the social activities that he was encouraged to do, involved food. There were cookery groups, going out for cake and coffee, little parties, barbecues and so on. The meals were also quite hearty and there was a special 'takeaway' evening.
I am not criticising the service at all, but there was such a strong association between positive action and eating, that most of the residents did put on a considerable amount of weight. Now he is in supported living, he eats because he is lonely or bored.
I am only giving my son as an example of some of the factors that may lead to overeating and obesity. Our drinking culture is another factor.
Ideally, there should be a holistic approach to obesity, combining education, with a greater variety of appetising and convenient 'healthier' foods. Swimming and gym classes could be subsidised for people on low incomes. Greater opportunities for social interaction that may counter the isolation that may lead to overeating, and much more availability of mental health services.
It is going to take time, but with the correct investment, our society can be healthier.