Try, if possible, to ascertain the cause of the weight loss or inability to gain weight. It can be caused by intestinal parasites or liver and pancreas problems. It can be caused by digestive enzyme deficiency, allergy, or food sensitivity. Problems in the thyroid, pancreas, or adrenal glands can make weight gain impossible. Hypoglycemics and diabetics have an especially hard time maintaining proper weight.
Zinc deficiency can reduce appetite, and so can some wasting diseases, such as cancer.
The consistency of the bowel movement and a check for undigested foods can be a valuable diagnostic aid. The experts tell us that, for adults, weight should not be gained at the rate of more than a pound a week. You should especially be concerned about an infant or small child who suddenly seems to stop gaining weight normally. Your body is having a hard time meeting the challenges of life, and needs help. For some people, it should include more calories and protein than should normally be eaten.