4-3b Listening - Obesity

Settle down, everyone. Let's get started. As you hopefully know, we are continuing our look at obesity today, and now that we've seen the state of obesity and some of the negative consequences it can have, we'll turn our focus towards some of the factors that can lead to obesity. Of most importance are two categories of causes that we'll look at, and those are genetic and environmental ones. You know the way of looking at many things. Is it nature or nurture, biology or learning? Is it something in our DNA, or did we get it from those around us socially, right?

Settle down, everyone. Let's get started. As you hopefully know, we are continuing our look at obesity today, and now that we've seen the state of obesity and some of the negative consequences it can have, we'll turn our focus towards some of the factors that can lead to obesity. Of most importance are two categories of causes that we'll look at, and those are genetic and environmental ones. You know the way of looking at many things. Is it nature or nurture, biology or learning? Is it something in our DNA, or did we get it from those around us socially, right?

So genetics. Genetics have definitely been shown to have a strong correlation with incidence of obesity. Some studies, which have looked at children who have been adopted by other families, have been very telling. When the weight of adopted children, those raised separately from their biological parents in a different environment, is compared to that of their birth parents, there is an extremely high degree of correlation. That is, up to 80% of the time, the adopted child's weight matches the weight of their biological parents, not the adoptive ones. That definitely shows there must be some type of genetic factors at play. It is thought that as much as 40% of why a person becomes obese could be based on these genetic factors alone.

The next question is, what is it genetically that seems to be causing obesity at all? There seem to be two hormones in the body that are contributing to this, namely leptin, that's L-E-P-T-I-N, and ghrelin, that's G-H-R-E-L-I-N. Leptin is a hormone that is secreted from fat cells and makes its way to the hypothalamus, which is a gland in the brain that helps regulate appetite. When there is excess leptin, it suppresses appetite and increases energy used, therefore causes a person to burn or reduce fat. The interesting thing is that obese individuals have high levels of leptin in their system, yet seem to have acquired some form of immunity to it through a genetic irregularity. The signals that would normally tell their body to stop eating and increase energy consumption do not get transmitted, and they continue to gain weight through excess fat.

The second hormone, ghrelin, seems to work in an opposite way. Whereas leptin lets the body know it has eaten enough, ghrelin signals the brain that the body is hungry and needs more food intake. If people have an overactive or increased production of ghrelin, this could cause false signals to be sent to the brain that the body is hungry and lead, of course, to further obesity. Scientists are looking closely at both of these hormones and trying to devise treatments that could hopefully combat obesity on a genetic level.

Well, as was mentioned, it's not all about genetics because the environment around an individual can also play a great role in someone becoming obese. One environmental factor that is often pointed to is the daily habits that people have, especially in modern times. Most studies show that modern industrialized societies, such as Canada, the United States, and countries in Europe, have far more cases of obesity. The argument is that with economic prosperity comes more abundance and access to more high-fat, unhealthy food sources. Some look at fast food outlets as a major contributor to this problem. By looking at any map produced by organizations such as the World Health Organization that shows levels of obesity, it's very easy to see how the most obese nations continue to be those that are industrialized and, well, rich. Societies that are poorly developed just don't have the same statistics.

As mentioned, these richer societies have a high-fat diet, and this is another factor, the type of food a society eats. Nations with developed economies tend to eat more unhealthy food in general. But on top of that is quantity. We, I guess I should count myself in this, we eat far more than other societies. Think about how much Canadians put on their plates when they eat. Compared with a typical meal in many Asian nations, where there is far, far less obesity, it's very excessive. It's no wonder there's more obesity.

A last environmental factor that leads to obesity, which can also be related to affluence in society, is the amount of exercise people get, or rather, the lack of exercise. In general, if people exercise less, they burn less energy and, therefore, store up far more fat than they dispose of. Some of this can be due to illness or old age, where people just become less physically able to be as active, and they gain weight as a result. Urbanization can also lead to this because modern conveniences of city life, such as easy transportation networks, and sedentary jobs, such as office work, cause people to move much less. Even once at home, with TV and personal computers, people do less physically than they may have years ago. Obesity continues to be a health problem that is increasing around the world. We seem to have a better idea as to how to treat the problem genetically and identify the factors in our lives that make us more prone to it, but eliminating it can be a much more difficult task.