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Obesity’s Epigenetic Legacy

By Charley Rees

New research in the field of obesity, a medical condition that affects approximately one hundred million Americans and over one billion people worldwide, has revealed that more factors play a role in determining weight than caloric intake. Such factors are present at a molecular level and interfere with the body’s ability to process hunger. Recent studies have uncovered that chemical groups, which are influenced by environmental factors, can sit atop the DNA and are heritable from generation to generation. This relatively new discovery, called epigenetics, is directly correlated with obesity and genetic issues today.

Epigenetic heritability plays an essential role in understanding the causes of obesity. One of the most striking examples of such heritability was depicted by the Dutch Hunger Winter. During World War II, 30,000 people in Holland starved due to a Nazi-imposed food embargo. Consequently, the children of the surviving population were subject to low birth-weights due to the malnourishment of their parents. This trend carried on so that the grandchildren of the survivors were also underweight at birth. Epigenetic heritability played a role in this phenomenon because chemical groups, which accumulated atop the genome during the Dutch Hunger Winter, were passed down genetically from the initial survivors. These chemical groups in turn affected the expression of various genes that dictated size within the genome, and when inherited, caused the generational smallness. 

We can apply the properties of epigenetic heritability to greater understand the issue of obesity. As stated previously, epigenetic factors can sit atop the DNA. By doing this, the factors either suppress or expose certain genes within the DNA. Within these genes lie various codes that specify for the production of certain proteins, which in turn execute the basic functions of life. Epigenetic factors can thus interfere with proper protein production and affect the natural processes of the body. When epigenetic factors suppress or expose the genes that deal with the body’s capacity to interpret satiety, signaling proteins that mandate food intake are no longer produced or produced in excess, and the result is obesity. These epigenetic factors are then passed down from generation to generation, making obesity perpetual. The interference with protein production and the heritability of the
epigenome show that epigenetics is essential to the issue of obesity.

Epigenetic factors, although they are heritable, can be altered and modified throughout one’s lifetime. A variety of environmental factors, such as diet and lifestyle, contribute to the accumulation of epigenetic factors. Healthy lifestyle practices, such as a balanced diet and exercise, discourage the accumulation of epigenetic factors on the genome and help clear existing chemical groups. The converse is also true, for living unhealthily makes it more likely for epigenetic factors to amass. It is therefore essential that “healthy living” be emphasized throughout society in order to control the accumulation of epigenetic factors that result in obesity. We must be able to maintain and monitor our epigenomes, if not for ourselves, then for our children who will inherit them.

Get the Skinny on the Fat

By Jillian Kohn and Emily Varua

People easily assume the causes of obesity. At first glance, it seems as if the only reason someone could be over the healthy weight for their height is their food intake and/or a lack of exercise. It is true that unhealthy eating habits can pertain to obesity, but your mind also tells you you are happy, making food a reward, therefore making you overeat. It is also true that a contribution to obesity is laziness. The ability to maintain your current weight, energy expenditure must equal energy intake. Aside from the basics, obesity can be caused by certain proteins in the body which interact with cell receptors or deficiencies in your genetics and/or epigenetics.

Essentially, your body’s regulation of body mass is controlled by the hormone proteins leptin, ghrelin and insulin. Leptin is an appetite suppressant, ghrelin an appetite stimulant, and insulin regulates the amount of glucose or sugar in the body that is later converted into fat.

Leptin levels play a key role in obesity because it tells you to stop eating. If someone is obese it could be related to being leptin deficient, meaning their body does not produce leptin or they could be desensitized to leptin which means their body no longer responds to that hormone, or their receptors are not responsive. The effect of gaining weight is not an immediate reaction, but rather a long term fat storage that our body processes for survival. Similar to the processes in which proteins are made, cell receptors are made. Receptors are carriers that proteins latch onto through cell specificity, which then grants the ability for proteins to perform their purpose. It can be compared to a car and its key. The key is the “receptor” that “latches” onto the ignition which then allows the car to start and carry out its function. Other than regulation defaults in these hormone proteins, there could be something wrong with the cell receptors. For example, if the receptor that corresponds with leptin does not respond, then your body will not know when to stop eating.

A relatively new discovery causing obesity has to do with epigenetics. 
Epigenetics are the chemicals that sit on top of your genome that blocks DNA from opening and transcribing, to make mRNA, to continue protein synthesis.
Your epigenome is unique because it can change throughout one’s lifetime and you can pass it down to your children.    

Many people say that obesity is genetic, which is partially true, but it can be much more complex, especially when you bring in epigenetics. Genes hold the blueprints for proteins which control almost everything in your body, but just because your parents are supposedly skinny does not mean you will be, since your epigenome can change throughout your lifetime. The detailed factors that make up obesity are easily overlooked, but are very complicated, as is the human body itself.

Students in Adriane Slaton’s biology class at Evanston Township High School are working on a project in which they are determining the effects of obesity and how obesity can be understood in many different ways scientifically. These papers by Charley Rees and by Jillian Kohn and Emily Varua are some of the results of that project.