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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
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.
Genetic Factors
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 Paradox
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 Factors
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.
Metabolism
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.
Eating Disorders and Medical Conditions
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.
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