Obesity is an excess of fatty tissue, with weight exceeding the ideal by
Morbid obesity is a term applied to individuals at least 50% above their
"ideal body weight" or 100 pounds in excess of their ideal body weight.
Greater than 40% of our population is 20+% above the "ideal" body weight,
while 20% is greater than 40% above this value.
A recent study estimates the annual cost of obesity and its complications
at approximately $40 billion, or approximately 5.5% of the United States
health care costs.
Obesity is multifactorial, with genetic, neurologic, behavioral, and
occasionally endocrinologic disorders playing a role.
The genetic tendency toward this disease is well-documented. Twin studies
reveal a higher rate of obesity within monozygotic twins than within dizygotic
twins. Studies in Denmark with adopted children found that a tendency toward
obesity correlates greater with the genetic than with the adopted parents.
Neurologically, certain lesions in the hypothalamus can provoke hyperphagia
and decreased activity, leading to obesity. There also is evidence linking
particular neurotransmitters to satiety or decreased appetite, such as
seratonin and the catecholamines. Glucagon also appears to promote satiety,
while insuline has been linked to increased appetite.
Behavioral factors run the gamut from learned dietary habits as children
to the vicious cycle, seen especially in adult-onset obesity, of depression
to overeating to excessive weight gain to worsened self image back to depression,
and so on.
Currently, identifiable endocrine disorders are felt to play a role in
less than 1% of the obese population. Thyroid disease is common-ly screened
for in this population, but in otherwise asymptomatic patients, it is an
The ancient Greeks realized that obesity was a health risk. Hippo-crates
wrote about lean people having fewer incidences of sudden death than obese
From the physiological perspective, adipose tissue can play a very useful
role as a thermoregulator (i.e., insulation) and as an energy reservoir.
The average individual falling within the "ideal body weight" guidelines
has approximately 100,000 calories stored as fat; obese individuals often
have many times this amount. Each pound of fat represents approximately
3500 calories of stored energy.
Often the visual perspective is enough to promote curiosity. Useful
tools such as the "body mass index" (Figure 1) and the "hip to waist ratio"
are available for more accurate delineation. Skin fold determinations also
are an accurate way to assess an estimated percentage of body fat. Other
modalities, including densitometry, ultrasound, and CAT scans have been
used to assess this disease.
The medical risks associated with this disease are legion.
Hyperinsulinemic states, glucose intolerance, and NIDDM are all closely
associated with obesity; 85% of NIDDM patients are obese.
Obese patients have a greater than 50% incidence of CAD than the general
population; among the mobidly obese, this figure rises to a greater than
90% increased incidence.
LVH and cardiac dilatation also are associated with obesity.
Hypertension is three times more common in the obese population. The Framingham
study reveals that, for every 10% weight increase above the "ideal," systolic
blood pressure rises approximately 6.5 mm/hg.
Some studies correlate obesity with lipid abnormalities.
Obesity causes an increased incidence of sleep apnea.
Obesity is associated with an increased incidence of venous disease, including
varicose veins and pulmonary embolism.
Risk factors for several cancer forms are increased by obesity, including
endometrial (x3), breast, colon, and prostatic cancers.
Obese individuals are at greater risk for the development of DJD.
Obese individuals have a higher incidence of gall bladder disease.
Individuals >50% above their "ideal body weight" have approximately twice
the mortality rate of the general population.
To be successful, a multifaceted treatment approch is necessary for
this multifactorial disease. These facets include proper diet, behavior
changes, and increased exercise. Additionally, medications and even surgical
interventions have been applied to combat obesity in certain patients.
Mild to moderate dietary restrictions (i.e., in the range of 1000 to 2000
calories per day) necessitate little medical supervision in the otherwise
healthy obese patient, as long as the diet fulfills all general nutritional
A very low calorie diet (i.e., in the range of 500 to 800 calories per
day) requires close medical screening and supervision. The so-called liquid
protein diets often fit into this category (Table 1). Unsupervised, these
diets can be very dangerous, and fatalities due to cardiac-related factors
have been associated with them.
Jaw wiring and in-hospital supervised starvation also have been used to
treat this disease.
Medications -- from amphetamines to thyroid preparations to diuretics --
have been employed to assist individuals in weight loss (Tables 2 and 3).
These often can produce results; however, if abused they carry significant
risks, and the results are often transient in nature -- so much so that
restrictions are steadily growing concerning their use in this area. Nevertheless,
research continues in this area, and a recent finding suggests that the
seratonin uptake inhibitors may promote weight loss in some individuals.
Surgical intervention -- from jejunoileal bypass to gastric stapling and
bypass -- also have been employed. Jejunoileal bypass resulted in significant
weight loss for the majority of selected patients; however, it had a very
high morbidity rate and considerable mortality risk. Gastric stapling procedures
averaged an approximately 60% excess weight loss. Morbidity and mortality
with this procedure are less than with the above procedure, but are still
real considerations. The recidivism rate, regardless of the intervention,
Exercise is essential to increasing energy expenditure and promote physical
D. Heard, MD