Several conditions can cause decreased appetite and increased thirst. According to the University of Maryland Medical Center, or UMMC, increased thirst, also known as polydipsia, is a fairly common symptom. However, increased thirst coupled with decreased hunger may signal a serious underlying condition that needs medical attention and intervention. A person experiencing loss of appetite and increased thirst should consult a qualified health care professional for a heath evaluation or assessment.
Anorexia nervosa may cause a loss of appetite and excessive thirst. Anorexia nervosa is an eating disorder associated with an unreasonable fear of gaining weight and an obsession with food. A person with anorexia nervosa attempts to maintain a weight that is at least 15 percent below normal for her age and height. Anorexia nervosa is most common among adolescent girls, although adolescent boys and even adults of all genders can develop this condition. Common signs and symptoms associated with anorexia nervosa include loss of appetite, increased thirst, extreme weight loss, fatigue, insomnia, brittle nails, thinning hair, absence of menstrual periods, constipation, cold intolerance, irregular heart rhythms and decreased blood pressure. MayoClinic.com states that certain risk factors may increase the likelihood of developing anorexia nervosa, including youth, female gender, genetics and participation in certain work, sports or artistic activities.
Diabetes insipidus can cause decreased appetite and increased thirst. Diabetes insipidus is a condition in which a person's kidneys are incapable of conserving water as they filter blood. The volume of water conserved by the kidneys is controlled by antidiuretic hormone, or ADH. ADH, also known as vasopressin, governs the re-absorption of molecules in the kidneys' tubules by affecting the tissue's permeability. According to the MedlinePlus website, there are two principle types of diabetes insipidus: central and nephrogenic. Central diabetes insipidus may be caused by head injury, infection, surgery or tumor, whereas nephrogenic diabetes insipidus may be caused by certain drugs and elevated calcium levels. Common signs and symptoms associated with diabetes insipidus include decreased appetite, excessive thirst and increased urine volume.
Diabetic ketoacidosis may cause a loss of appetite and excessive thirst. According to the American Diabetes Association, or ADA, diabetic ketoacidosis is a potentially life-threatening diabetes-related complication that occurs when a person's cells don’t receive adequate amounts of glucose. Diabetic ketoacidosis is caused by too little insulin in the body. Common signs and symptoms associated with diabetic ketoacidosis include loss of appetite, excessive thirst, frequent urination, nausea and vomiting, abdominal pain, weakness, fatigue, dyspnea or shortness of breath and fruity-smelling breath. Certain risk factors predispose a person to diabetic ketoacidosis, including having Type 1 diabetes and being under 19 years of age. MayoClinic.com states that diabetic ketoacidosis can usually be prevented in diabetics by regular monitoring blood sugar levels, adjusting insulin dosage as needed and checking ketone levels.