1. Neha Dronamraju
BIOL-40280
Introduction to Genetics and Human Disease
Prof. Lisa Lievense
8/19/16
The Impact of Genes on Obesity
Recently, I have become very conscious about fitness and health. I initially developed an
interest in living a healthier lifestyle because I wanted to lose weight. In a lot of fitness blogs and
magazines that I perused, healthy women are portrayed as supermodels; healthy is equated to
thin. Most fitness gurus are lean, tall, and toned. This is the body type many people, especially
adolescents, aspire to achieve when they start their fitness journey. Some people end up
achieving this ideal body type and others do not- even though they brave the same, rigorous
fitness and diet regimen. The difference in the end result for different people all ties back to
genetics. The genes associated with weight loss or weight gain are multifactorial or complex
traits, which means that both internal and external factors can influence a body type. It took me a
while to realize how big of a role genetics played in the way my body looks, and being aware of
my genetic makeup has allowed me to accept my physique for what it is. My interest in this topic
stems from my focus on maintaining a healthy weight and from my curiosity to understand all
factors that either support or conflict with my goal.
According to the world health organization, obesity is one of the primary contributors to
ill health. There are obvious environmental factors, which contribute to weight loss or weight
gain; the two most prominent being diet and exercise. The golden rule is if you burn more
calories than you eat, you will lose weight. However, genetics also plays a role in how
effectively one sheds body fat. Someone’s weight can have just as much to do with their
hereditary and ancestry as their fitness schedule. As of June 2009, more than 400 different genes
had been linked to obesity. Genes can contribute to weight in many ways including defining the
metabolism, cravings, body mass index, and appetite. The glutamic acid decarboxylase gene
(GAD2) is the most popular gene that is linked to obesity. It was first associated with the eating
habits and feeding behaviors of obese adults, and then reported to be hereditary after the same

2. behaviors were observed in the children of these adults. A recent study has found this gene to be
associated with type 2 diabetes as well.. Another gene, which controls a growth hormone
(GHSR), was identified in 1996, as having an impact on not just the weight of an individual, but
also their body type. This hormone is secreted by the stomach and small intestine and plays a
role in regulating appetite and controlling the functions of the stomach and intestine. It is also
associated with familial short stature or obesity syndrome (hereditary obesity). The two genes
described above are just a small subset in the vast study of a multitude of genes that have been
linked to the body weight of an individual.
A surprising fact I encountered in my research on this topic is that there are multiple
ways to tell how much of your weight depends on your genes. I learned that some patterns you
can observe are your fluctuations in weight throughout your life and your ability to lose weight
with a clean diet and rigorous exercise schedule. I also came across new statistics; such as if both
parents are obese, there is an 80% chance that the child will also be obese. This is linked to both
genetics and environmental factors- a gene could have been passed from parent to child or the
child could be influenced by his or her parents’ eating habits.
The class discussion about epigenetics and multifactorial traits supplemented me with
basic knowledge and support as I progressed in my research. When obesity genes are passed
down from a parental unit, the gene is affected by an epigenetic mark. Our genome contains the
information to make us who we are but it is actually gene regulation that determines our behavior
and appearance. Epigenetics directly affects the gene regulation, consequently affecting our
physical characteristics, including weight. The research I did for this topic required an
understanding of epigenetic mechanisms and how they control the metabolic process. Through
our discussion board and reading about epigenetics in week five, I was able to make connections
to my topic. Our study of multifactorial traits during week three was especially relevant to my
research on genetic factors that control BMI and body type. My previous theory that body
weight is influenced by only diet and exercise was debunked; the lesson on multifactorial traits
clarified that genetics could have as much bearing on ones ability to lose weight as external
factors. I understand now the reason some people lose weight easily and others cannot, and this
insight allows me to be kinder on myself as I pursue my fitness goals.

3. Works Cited
"Why People Become Overweight - Harvard Health." Harvard Health. N.p., June 2009. Web. 17
Aug. 2016.
http://www.health.harvard.edu/staying-healthy/why-people-become-overweight
Herrera, Blanca M., Sarah Keildson, and Cecilia M. Lindgren. "Genetics and Epigenetics of
Obesity." Maturitas. Elsevier/North Holland Biomedical Press, May 2011. Web. 16 Aug. 2016.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3213306/
Youngson, N. A., and M. J. Morris. "What Obesity Research Tells Us about Epigenetic
Mechanisms." Philosophical Transactions of the Royal Society B: Biological Sciences 368.1609
(2012): 20110337. Web.
http://rstb.royalsocietypublishing.org/content/royptb/368/1609/20110337.full.pdf
"The Epigenetics of Obesity - Endocrine News." Endocrine News. N.p., 26 Feb. 2016. Web. 13
Aug. 2016.
http://endocrinenews.endocrine.org/the-epigenetics-of-obesity/
"Study Describes Epigenetic Shifts Linking Obesity, Diabetes." GenomeWeb. N.p., n.d. Web. 15
Aug. 2016.
https://www.genomeweb.com/epigenetics-research/study-describes-epigenetic-shifts-
linking-obesity-diabetes