Risks of Low Body Mass

A low body mass index, or underweight, describes a weight that's below the healthy range. It defines the status of decreased body fat stores and emaciated lean muscle mass. However, having a low body mass does not only affect the skeletal muscle bulk and the total body fat. Being underweight causes an increased risk for many health problems and diseases and serves as an indication for medical attention.

Decreased Fertility in Women

Abnormal menses and decreased level of fertility may occur in women with a low body mass index. In the worst cases, amenorrhea, or the absence of menstruation, may also happen. According to a study published in the June 2006 issue of the "British Journal of Sports Medicine," having an adequate amount of fat coincides with the regularity of periods, while decreased body fat may affect the menstrual cycle.

Decreased Immune System Function

The immune system serves as the body's defense against bacterial, viral and fungal infections. A study published by "The Journal of Nutrition" in May 2006 states that having protein-energy malnutrition, a common cause of low body mass, may contribute to the decreased viral immunity and diminished activity against infections. The inability to meet the energy demands of the immune system, a common occurrence in underweight patients, may serve as the main cause of this diminished immune response function.

Increased Mortality

A study published in the 2003 issue of the "Journal of Epidemiology and Community Health" suggests that patients with a low body mass may have a higher risk of mortality caused by cardiovascular and respiratory diseases compared to patients with a normal body mass. However, the researchers failed to demonstrate this pattern in mortalities caused by cancer problems.

Energy and Nutritional Deficiencies

NHS choices mentions that being underweight may result in energy and nutritional deficiencies. Lack of energy leads easy fatigue and tiredness. Having a low body mass may signify a deficiency in the important vitamins and minerals needed for essential body processes.