Symptoms, when underweight, is a problem to be addressed. These symptoms include hunger, dizziness, fatigue, weakness, sensitivity to cold, and loss of ambition. Underweight is a problem for some, but not for others. Actually, as one ages, underweight can be an advantage in a number of ways. If you are in good health, although underweight, there may be no need for concern to gain weight.
Underweight people live longer and are in less danger from heart disease.
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.