The main reasons for the gradual weight loss of the body are as follows: First, there may be any chronic wasting diseases, such as hyperthyroidism, tuberculosis and diabetes. Second, there may be some malignant diseases, such as malignant transformation of some tumors. As for the lack of nutritional intake, the possibility is very small. The problem now is that I don't know your more detailed situation, or even your age, so I can only make a general reference.