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Lesson Seven: Obesogens

Module One: The Obesity Epidemic

Overview

Video Lecture

US Obesity Map, 2007

Click the online lecture for the details necessary to understand this module's key ideas.

Learning Objective

At the end of this module, students will be able to:

Explain why it is reasonable to examine how endocrine disrupting chemicals (EDCs) could be a factor in the rise of obesity rates in the United States and other countries around the world.

Almost 34% of adults in the United States are fat enough to define them as “clinically obese” (this means they have a body mass index over 30). The cost of caring for this group of some 60 million people runs in the billions of dollars annually, although exactly how many billions is controversial. There’s no controversy, however, about the damaging effects of clinical obesity. Those who fall into this category are more likely to suffer from type 2 diabetes, cardiovascular disease, cancer, and other life threatening conditions.

Although too many calories consumed coupled with too little exercise can certainly result in obesity, new research indicates that “couch potato syndrome” is only one of several reasons why we are growing, as a group, more overweight.  Stress, viruses, and genetics also play a role. Evolutionary adaptations that remain with us today (such as the “thrifty” genes that helped us survive in our hunter-gatherer past) may also affect our body weight.  We are also learning that our tendency to gain weight during life can begin even while we’re still in the womb.

In addition to these forces, could modern chemicals also play a role in rising obesity rates?  There is a correlation between the increase in the number and amount of chemicals we are being exposed to and the obesity epidemic.  Although correlation doesn’t equal causation, there is reason to believe that the two are related.  In previous lessons, you learned about Endocrine Disrupting Chemicals (EDCs) that either mimic or disrupt the actions of hormones. Since the production and storage of fat in the human body is also under the direction of hormones, this module asks, “Can certain kinds of endocrine disrupting chemicals contribute to obesity?”

To explore this module's material in depth, view the lecture.

Key Points

  • Obesity is a major problem.
  • Imbalance in the caloric checkbook—“more calories consumed than burned” is not always the sole reason for obesity—there are many other factors, including genetics and environment.
  • We know that chemicals can change the endocrine systems of humans by affecting gene expression, so it’s worth looking into whether chemicals can be part of the cause of the obesity epidemic.