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Studies have shown that an amino acid, tryptophan, increases in the
blood when a person eats carbohydrates. Carbohydrates also stimulate the
secretion of insulin, which speeds the uptake of tryptophan into the central
nervous system. The tryptophan is then converted to serotonin in the brain.
Based on the fact that many depressed and obese people have low serotonin
levels and carbohydrates can stimulate serotonin production, many
researchers now believe that obese and depressed people are in a sense using
food as a medication. The body recognizes serotonin deficiency and triggers
the desire for serotonin-friendly foods, specifically carbohydrates. A cycle of
feeling blue, craving carbs, eating carbs, feeling better, then feeling blue
again sets in. The cycle repeats, and leads to weight gain.
Most overweight people crave (and overeat) carbs more than people of
“normal” weight. In fact, researchers estimate that as many as two-thirds of
those with BMIs over twenty-five are carbohydrate-cravers. Abnormally low
serotonin levels could, in effect, be causing their overweight and obesity.
Uncontrollable weight gain might just come down to brain chemistry.
Self-consciousness, isolation, rejection, low self-esteem, distorted body
image, self-deprecation, feelings of failure, depression, and even suicide: all
can be potential psychological side effects of obesity. Again, not everyone
88 / Health Issues Caused by Obesity
Research Project
Think about the beliefs people have about obe-
sity, such as that people who are obese are lazy
and don’t exercise. Write down all of the causes
of obesity that you know of. This chapter has
given you a couple, such as genetics. Now go to the library
and find other causes for obesity. Do some of the results
surprise you? Write down all of the causes of obesity that
you were unaware of.