It is common to think that someone with a so-called healthy body weight has good nutrition. However, body weight is a reflection of stored calories, not an indicator of nutritional health.

Although body weight can affect the need for certain essential nutrients — such as protein — deficient or excessive intake of vitamins and minerals can occur at any weight. At least partly due to a natural bias equating healthy weight with overall health, normal-weight people with nutrient-related health problems often may be misdiagnosed and treated for their symptoms rather than for the real cause of their problems.

Question: What are essential nutrients?

Answer: The simple definition of an essential nutrient is a dietary substance required for basic functions of the body such as growth, repair and reproduction. The six main categories include macronutrients needed in large amounts (water, protein, fat, carbohydrate) and micronutrients (vitamins and minerals). Even though vitamins and minerals are needed in very tiny amounts, they are as essential as the calorie-containing macronutrients.

Q: What nutritional deficiencies or excesses mimic or cause symptoms of medical conditions?

A: Essentially all nutrient deficiencies or excesses can be misdiagnosed. For example: Water deficiency can cause headaches, constipation, nausea, dizziness, confusion and leg cramps, to name a few. Water toxicity can cause a condition called hyponatremia (extremely low blood sodium) and can be fatal.

Inadequate iodine can affect growth and even cause a goiter (enlarged thyroid gland). Risk of this increases in those who consume excessive amounts of foods with goitrogens that block normal iodine function (cabbage family and various beans). Excess iodine also disrupts thyroid function, potentially causing either hyper- or hypothyroid conditions. Excessive consumption of some types of edible seaweed can cause this.

Consuming either inadequate or excessive dietary calcium can trigger the development of kidney stones.

Magnesium deficiency can cause muscle spasms, loss of appetite, nausea and vomiting to name a few issues. Excess magnesium (generally from excess supplements) can cause diarrhea, severe fatigue, confusion, heart rhythm disturbances and kidney problems.

Both iron deficiency and iron excess can cause a variety of potential health symptoms such as fatigue, digestive problems, insomnia, depression, breathing problems, inability to concentrate and excessively low blood pressure. Frequently, since iron deficiency can develop so gradually, many people perceive their increasing fatigue as just their “new normal.”

Manganese deficiency can cause impaired growth and reproduction, skeletal problems and impaired glucose tolerance. Manganese excess can cause cognitive and behavioral problems and even tremors resembling Parkinson’s disease.

These are but a few examples of symptoms associated with inadequate or excess amounts of essential nutrients. As you can see, malnutrition can greatly complicate a diagnosis of the causes of a variety of symptoms, making it difficult to provide the best treatment. Identification of nutrient deficiencies can be difficult, so take care to meet your nutrient needs by eating a wide variety of wholesome foods from within each of the food groups.

Alan Titchenal, Ph.D., C.N.S., and Joannie Dobbs, Ph.D., C.N.S., are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii-Manoa. Dobbs also works with University Health Services.