Overweight Vs. Underweight

Having overweight or underweight can have negative impacts on your health. Maintaining a healthy weight is part of maintaining a good nutritional status, which can lower your risk for chronic diseases.

Less than 2 percent of adults in the United States are underweight, while 69 percent have overweight or obesity, according to research published in the November 2007 edition of the "Journal of the American Medical Association." If you're at either end of the spectrum, you may need to make lifestyle changes so you can achieve and maintain a healthy weight.

Measuring Mass

The Centers for Disease Control and Prevention uses the body mass index, or BMI, to categorize an adult’s weight status. You can calculate your BMI by dividing your weight, in kilograms, by the square of your height in meters, or by using an online BMI calculator. The CDC considers a BMI of less than 18.5 to be underweight and a BMI of 25 or greater as overweight. For adults, a BMI of 30 or greater indicates obesity.

Causes of Underweight and Overweight

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An imbalance between calories consumed and calories expended leads to underweight and overweight. Underweight results from expending more calories than you consume, which can occur when you exercise excessively, dramatically limit your food intake or have a health condition that increases nutrient needs or reduces nutrient absorption.

Overweight results from an excess of calories. Contributing factors can include genetics, certain medications, inadequate physical activity and eating an abundance of high-calorie foods, including fast foods, and processed foods, such as cookies and cakes.

Health Concerns

Underweight and overweight are both risk factors for premature death, according to findings published in 2007 in the "Journal of the American Medical Association." Being underweight can increase your risk for osteoporosis, or thinning of the bones, which can increase your risk for bone fractures later in life.

Overweight and obesity can increase your risk for osteoarthritis, heart disease, type 2 diabetes, certain cancers, stroke, liver disease and respiratory conditions, such as asthma and sleep apnea.

Underweight people, however, might be at a slightly higher risk for complications. Research conducted in 2013 by researchers at Toronto's St. Michael’s Hospital suggests that people who are clinically underweight have a 1.8 times greater risk of dying than people at normal weight. People with obesity have a 1.2 times greater risk of dying than those with normal weight.

Nutritional Interventions

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Gaining weight requires that you take in more calories than you consume. To increase your calorie consumption, add calorie-dense foods, such as nuts, avocados, dried fruit and whole grains, to your diet. To lose weight, place a dietary emphasis on low-calorie foods, such as vegetables, fresh fruits, lean proteins and low-fat dairy products.

Choose nutrient-dense foods whether you want to gain or lose weight, as this will help prevent overeating by filling you up while ensuring you aren't eating empty calories -- foods devoid of nutritional value. Consult a medical professional if you have underweight or overweight so you can determine the causes and your best course of action.