Body habitus, or simply habitus, is a medical term for “physique” or “body type.” A wide range of factors can determine body type, and medical professionals often make a note of a patient's habitus on his or her chart as part of a general reference to provide information about the patient's history. Some studies also suggest that certain extremes in physique can be indicators of disease or may lead to certain illnesses.
There are three terms commonly used in reference to body habitus. A patient with an ectomorphic body type is said to be underweight, a patient with a mesomorphic body type is of normal weight, and a patient with an endomorphic body type is overweight. The thresholds of “underweight,” “normal,” and “overweight” have been adjusted on many occasions, and there is some conflict in the medical community about where the dividing lines should fall.
In terms of weight, a number of factors can influence physique. Genetics plays an important role, as do issues such as the balance of neurotransmitters in the brain, a person's level of activity, and their diet. While the news media often suggests that being extremely under or overweight can be dangerous, in-depth scientific research indicates that the situation is actually not this simplistic, and that while weight can play a role in health, weight and health are not directly correlated.
Other terms used in reference to body habitus may describe features such as musculature or strength, along with other characteristics of interest. As a general rule, any change in the physique can be a cause for concern. Many diseases cause patients to gain or lose weight, making changes in body size an indicator that a patient is experiencing a problem; AIDS, for example, is closely associated with emaciation. Patients may also embark on activities which change their body shape, such as when a patient becomes more athletic and develops increased musculature.
Many medications can induce changes in the body, especially if used in the long term. Steroids, for example, are infamous for causing a variety of changes. While these drugs are often associated with attempts to increase strength and musculature, they are also used in the treatment of a wide range of diseases. People who have taken steroids long-term for any reason often develop tell-tale physical signs, such as a distinctive “buffalo hump” on the upper back. Other medications can lead to decreased musculature, weight gain, and changes in the distribution of fat on the body.