Psychologists are permitted to share informed opinions based in sound psychological theory. If you were interested, you would read the excellent works tracing fatness to early experiences of childhood abuse and trauma; yo-yo dieting and/or unhealthy diet patterns of deprivation begun in childhood; that interpret the links between fatness and diseases like PCOS, auto immune diseases, endocrine or hormone imbalances, diabetes, or weight gain caused by medication.
You skip over these categories as though they affect only tiny numbers of people. In fact, millions of people worldwide suffer from these diseases and these forms of trauma. Few offer a quick fix, medical or otherwise.
You are apparently educated. How can you be so stupid?