Morbid obesity and anorexia nervosa (AN) are serious health problems with devastating consequences. Nevertheless, the aetiology of them is still elusive. By natural weight loss, one of the authors of this paper experienced a process from overweight to AN. And by adopting the anorexic Luigi Cornaro diet, he recovered from AN. Based on his unique experience, we hypothesize that the sustained up-regulated autophagy (SUA) without anorexia is the mechanism behind morbid obesity and AN. The main feature of a person with fully developed SUA without anorexia is that, starvation becomes anxiolytic, and normal eating is quite stressful. As SUA perpetually provides the host with plenty of recycled energy and nutrients from each cell of the body, daily regular restrictive eating becomes a natural requisite. Failing which and eating normally will lead to morbid obesity. At the other extreme, eating too less or long time fasting will result in atypical AN or AN. Patients with morbid obesity, atypical AN or AN are thus forced to adopt the Luigi Cornaro diet of eat-but-little. In this way, they can maintain or restore the homeostasis of their gut mucosa and healthy body weight, and lead an illness-free long life. As a precaution, we suggest that the attitude of a person towards normal eating and starvation should be a diagnosing criterion to determine the degree of a person in development of SUA in his body, and carry out early intervention if he is found to be prone to morbid obesity, AN or AAN.
YU BX, Yu BW and Yu LG