Poor nutrition may be one of the easiest conditions to self-diagnose. Look at the food pyramid and the suggested servings. Look at your diet. Are you getting the recommended daily amounts of fruits and vegetables? Enough calcium? Read the labels and compare what you eat to what you need. You may discover that even if your weight is ideal, you are not getting enough nutrition.

Poor nutrition can manifest itself in many ways. The more obvious symptoms of a nutritional deficiency include dull, dry or shedding hair; red, dry, pale or dull eyes; spoon-shaped, brittle or ridged nails; bleeding gums; swollen, red, cracked lips; flaky skin that doesn't heal quickly; swelling in your legs and feet; wasted, weak muscles; memory loss and fatigue.

Underweight and Nutritional Problems

It's not always easy to tell why you are underweight, but being underweight often coincides with nutritional deficiencies which can show up in the symptoms described above. There are other potential dangers with being underweight, however. Thus, your health care professional should test levels of:

• Electrolytes, to check for dehydration, malnutrition, self-induced vomiting and laxative and/or diuretic abuse.

• B12 and folic acid. These vitamins play a role in depression and anxiety. Additionally, lack of B12 and folic acid is associated with problems with protein, carbohydrate and fat metabolism, and with your body's ability to absorb nutrients.

• Blood glucose (blood sugar). Elevated or low blood sugar levels can be dangerous.

• Liver function levels. Checks for gallbladder disease, liver disease, excessive exercising or even a heart attack.

• Cholesterol. High cholesterol levels are more common in those who have problems with binging and anorexia.

• Thyroid function tests. These rule out any possible problems with the thyroid gland, which can affect weight loss and gain.

• Urinalysis. This tests for a variety of systemic diseases and gauges kidney function, urine sugar and ketone levels. Ketones can quickly accumulate in the blood when the body is deprived of food and nutrients. Too much, and it can lead to coma and death.

Your health care professional may also take a blood pressure reading, a bone density test, test your red and white blood cell counts and perform an electrocardiogram to check your heartbeat.

Young Women and Eating Disorders

If you lose weight suddenly or for unknown reasons, talk to your health care professional immediately. Unexplained weight loss may indicate a serious health condition. And even if it doesn't, simply being underweight is linked to menstrual irregularity, menstrual cessation (and sometimes, as a result, dental problems, such as erosion of the enamel, and osteoporosis) and a higher risk of early death.

While it's important to maintain a healthy weight and lose excess weight, excessive concern about weight may lead to eating disorders that include overexercising, self-induced vomiting and the abuse of laxatives or other medications.

More than 90 percent of those afflicted with eating disorders are adolescent and young adult women. One reason that women in this age group are particularly vulnerable to eating disorders is their tendency to go on strict diets to achieve an "ideal" figure. Researchers have found that such stringent dieting can play a key role in triggering eating disorders.

Approximately one percent of adolescent girls develop anorexia nervosa, a dangerous condition in which they can literally starve themselves to death. Another two percent to three percent of young women develop bulimia nervosa, a destructive pattern of excessive overeating followed by vomiting or other "purging" behaviors to control their weight.

Not everyone who is underweight suffers from an eating disorder, but it is a serious problem affecting more than seven million American women. Women with anorexia nervosa starve themselves and/or exercise excessively, losing anywhere from 15 percent to 60 percent of their normal body weight. Some die. Women with bulimia nervosa binge on large quantities of food-up to 20,000 calories at one time-and then try to get rid of the excess calories. Some purge by inducing vomiting, abusing laxatives and diuretics, or by taking enemas. Others fast or exercise to extremes.

But it's important to note that the problem here isn't food: Eating disorders are disorders that need to be treated by a psychiatrist and/or psychologist.

If you have an eating disorder, you not only run the risk of nutrition deficiencies, but damage to your throat and teeth (from vomiting), your bones (from lack of calcium and vitamin D) and your heart (from imbalanced electrolytes), among other problems.

A similar disorder is binge eating disorder, which involves uncontrolled eating without purging. Another disorder, "eating disorders not otherwise specified" (EDNOS), refers to symptoms that don't fit into the other two categories of eating disorders.

Treating Eating Disorders

Not every underweight woman has an eating disorder. But for those who do, treatment is difficult and can require a team of health care professionals, including a dietitian, psychologist and physician. Methods include:

• Weight and eating normalization

• Psychotherapy (individual, group and family). Two specific types of psychotherapy have been found to help: cognitive behavioral therapy and interpersonal therapy

• Medical evaluation to stabilize you physically

• Nutritional counseling

• Medications for bulimia nervosa or to prevent relapse in women with anorexia nervosa who have managed to regain lost weight.

Aging and Nutrition Problems

As you age, you may have difficulty getting and absorbing certain nutrients.

Older people may not get the nourishment they need for several reasons:

Difficulty chewing. Substitute softer foods, such as puréed and cooked fruits and vegetables and juices, ground meats and dairy foods (unless you have lactose intolerance).

Loss of taste. Some medicines alter your sense of taste making you lose your appetite. Ask your health care professional if there are alternatives to the medicine you're taking. You might also experiment with spices to make foods tastier. Also, rotating tastes of each food on your plate, rather than eating one food at once, can help you taste various flavors better. Foods with strong scents also taste better, since taste and smell are linked.

Loneliness. If you don't feel that cooking a healthful meal is worth the bother just for yourself, try to eat with family or friends whenever possible, or try a senior center nutritional program.

Stomach upset. Identify triggers and make substitutions. For example, if milk disagrees with you, try cream soups, yogurt and cheese to get your calcium. Likewise, swap troublesome vegetables like cabbage and broccoli for gentler ones, such as potatoes, green beans and carrots. Try fruit juices instead of fresh fruit.

Difficulty preparing healthful meals. Because of the advent of healthful ready-to-eat meals or a daily visit from a care provider (such as Meals on Wheels), an elderly woman can have both convenience and nutrition.

Medications. Some medications block or hamper absorption of certain nutrients in addition to hampering your ability to taste food. Talk to your health care professional about alternatives if this is a problem for you.

It's also important that you get enough liquid, since you may have a decreased sensitivity to thirst. Make it a priority to sip from a glass of ice water or other low calorie, low sugar beverage throughout the day.

Given the possibility of nutrient deficiencies in the elderly, talk to your health care professional about the possibility of supplementing your diet with calcium, vitamin D and vitamin B12.

Food Allergies and Intolerances

Everyone seems to have food allergies these days, but, in fact, such allergies are rare. According to the American Dietetic Association, while one in three adults believes they have a food allergy, only about one percent actually do.

Actually, more people suffer from food intolerances, which don't involve the immune system. However, food intolerance symptoms—such as intestinal distress—may mimic those of a food allergy. If you have a food intolerance, talk to a nutritionist about diagnosis and treatment; if you have food allergies, you need to see an allergist. Whether you have food allergies or intolerance, you will need to develop a diet that fits your needs and avoids foods that trigger a reaction.