The reasons for obesity are multiple and
complex. Despite conventional wisdom, it is not simply a result
of overeating. Research has shown that in many cases a significant,
underlying cause of morbid obesity is genetic. Studies have
demonstrated that once the problem is established, efforts such
as dieting and exercise programs have a limited ability to provide
effective long-term relief.
Science continues to search for answers. But until the disease
is better understood, the control of excess weight is something
patients must work at for their entire lives. That is why
it is very important to understand that all current medical
interventions, including weight loss surgery, should not be
considered medical cures. Rather they are attempts to reduce
the effects of excessive weight and alleviate the serious
physical, emotional and social consequences of the disease.
Contributing Factors
Genetic Factors
The Pima Paradox
Environmental Factors
Metabolism
Eating Disorders &
Medical Conditions
The underlying causes of severe obesity are not known. There
are many factors that contribute to the development of obesity
including genetic, hereditary, environmental, metabolic and
eating disorders. There are also certain medical conditions
that may result in obesity like intake of steroids and hypothyroidism.
Numerous scientific studies have established that your genes
play an important role in your tendency to gain excess weight.
- The body weight of adopted children shows no correlation
with the body weight of their adoptive parents, who feed
them and teach them how to eat. Their weight does have an
80 percent correlation with their genetic parents, whom
they have never met.
- Identical twins, with the same genes, show a much higher
similarity of body weights than do fraternal twins, who
have different genes.
- Certain groups of people, such as the Pima Indian tribe
in Arizona, have a very high incidence of severe obesity.
They also have significantly higher rates of diabetes and
heart disease than other ethnic groups.
We probably have a number of genes directly related to weight.
Just as some genes determine eye color or height, others affect
our appetite, our ability to feel full or satisfied, our metabolism,
our fat-storing ability, and even our natural activity levels.
The Pima Indians are known in scientific circles as one of
the heaviest groups of people in the world. In fact, National
Institutes of Health researchers have been studying them for
more than 35 years. Some adults weigh more than 500 pounds,
and many obese teenagers are suffering from diabetes, the
disease most frequently associated with obesity.
But here's a really interesting fact - a group of Pima Indians
living in Sierra Madre, Mexico, does not have a problem with
obesity and its related diseases. Why not?
The leading theory states that after many generations of
living in the desert, often confronting famine, the most successful
Pima were those with genes that helped them store as much
fat as possible during times when food was available. Now
those fat-storing genes work against them.
Though both populations consume a similar number of calories
each day, the Mexican Pima still live much like their ancestors
did. They put in 23 hours of physical labor each week and
eat a traditional diet that's very low in fat. The Arizona
Pima live like most other modern Americans, eating a diet
consisting of around 40 percent fat and engaging in physical
activity for only two hours a week.
The Pima apparently have a genetic predisposition to gain
weight. And the environment in which they live - the environment
in which most of us live - makes it nearly impossible for
the Arizona Pima to maintain a normal, healthy body weight.
Environmental and genetic factors are obviously closely intertwined.
If you have a genetic predisposition toward obesity, then
the modern American lifestyle and environment may make controlling
weight more difficult.
Fast food, long days sitting at a desk, and suburban neighborhoods
that require cars all magnify hereditary factors such as metabolism
and efficient fat storage.
For those suffering from morbid obesity, anything less than
a total change in environment usually results in failure to
reach and maintain a healthy body weight.
We used to think of weight gain or loss as only a function
of calories ingested and then burned. Take in more calories
than you burn, gain weight; burn more calories than you ingest,
lose weight. But now we know the equation isn't that simple.
Obesity researchers now talk about a theory called the "set
point," a sort of thermostat in the brain that makes people
resistant to either weight gain or loss. If you try to override
the set point by drastically cutting your calorie intake,
your brain responds by lowering metabolism and slowing activity.
You then gain back any weight you lost.
Weight loss surgery is not a cure for eating disorders. And
there are medical conditions, such as hypothyroidism, that
can also cause weight gain. That's why it's important that
you work with your doctor to make sure you do not have a condition
that should be treated with medication and counseling.
