Although unpleasant, nausea and a loss of appetite are generally not harmful to the body. Nausea can occur for a variety of simple reasons, including simple food aversions, pregnancy and fear. Loss of appetite, or anorexia, generally follows a bout of nausea, as the stomach has no desire to welcome food. Occasionally, these trivial symptoms continue long enough to lead to weight loss. At this point, the condition becomes quite serious and dangerous.
Infection and Disease
The University of Illinois Medical Center at Chicago says a wide variety of diseases and infections can cause nausea and loss of appetite. Infections might include influenza, kidney infection and hepatitis, while diseases might include cirrhosis of the liver, congestive heart failure and pancreatitis. These examples are only a few of the many conditions that cause nausea and anorexia. As these infections and diseases overwhelm the body, a variety of cells and chemicals are released to fight off the intruders. Although these chemicals are helpful to the body, they cause a severe loss of appetite. As the disease runs its course, weight loss is likely to occur.
Patients with anorexia nervosa exhibit an unusual obsession with food and weight loss, often starving themselves to achieve a lower weight. Although the condition can occur in men or women of any age, anorexia nervosa is most common among female teenagers. In an effort to lose weight and achieve a thinner body, patients with anorexia refuse to eat. Over time, this deliberate avoidance of food causes the mind to reject the idea of food. Although the patient may be biologically hungry, she has no appetite and feels nauseated at the thought of food. Naturally, a dangerous amount of weight loss occurs.
A variety of emotional disorders, including depression, anxiety and stress, cause a general loss of appetite. As the Conquering Stress website says, "no one feels like eating when they're frightened, panic-stricken or feeling worthless and exhausted." During times of emotional distress, the mind becomes overwhelmed by its own distress and disregards many biological needs, such as hunger. If the emotional disorder goes unresolved, continued loss of appetite leads to unhealthy weight loss and significant lack of energy.
Drug Side Effects
Nausea and loss of appetite are common side effects of various medications. These side effects are not detrimental if a person is only required to take the medication for a few days. However, the symptoms may never dissipate if regular use of the medication is necessary. For example, the drugs used in chemotherapy are known to trigger these symptoms. In fact, the Cancer Connect website says "cancer treatments first cause a loss of appetite or aversion to food, also known as anorexia, which then may lead to drastic weight loss."
If the nausea and loss off appetite occur long enough to trigger weight loss, the body is likely experiencing malnutrition, "a lack of necessary food and nutrients in the body," the University of Illinois Medical Center at Chicago says. Other dangerous side effects include dehydration, anemia, electrolyte imbalances, kidney problems and heart problems. If the nausea, anorexia and weight loss continue for a long period of time, they may eventually lead to death.