What Causes Obesity?
Most likely many, many, many things.
By: Dr. Eeks
In June of 2013, and after much debate, the American Medical Association labeled obesity a “disease.” As soon as I read about the AMA’s decision, I posted the news to the Blooming Wellness Facebook page and asked people what they thought. Some agreed with the AMA’s new label, however others were quite upset and argued that obesity is a choice and manifests out of laziness and lack of personal responsibility. I was torn over the AMA’s decision, and after careful consideration of the available evidence, I’m still torn. I know obesity is a problem, considering one fifth of children and one third of adults are obese. That said, I have made two conclusions. One is that what causes obesity involves much more than the sole variable personal responsibility, and the other is that there needs to be a stronger holistic approach to obesity.
First I asked myself, “What is a disease?”
According to the Merriam-Webster online dictionary a disease is, ” an impairment of the normal state of the living animal or plant body or one of its parts that interrupts or modifies the performance of the vital functions, is typically manifested by distinguishing signs and symptoms, and is a response to environmental factors (as malnutrition, industrial hazards, or climate), to specific infective agents (as worms, bacteria, or viruses), to inherent defects of the organism (as genetic anomalies), or to combinations of these factors.”
Does obesity create an, “Impairment of the normal state of the living animal or one of its parts that interrupts or modifies the performance of its vital functions?”
Yes, I think it can be argued that obesity impairs one’s normal state. It interferes with one’s daily activities. Being overweight can and will slow someone down. Having excess body fat is proven to put us at greater risk for cardiovascular disease, diabetes, fungal infections and even cancer. It affects blood lipids, cholesterol levels, kidney function, liver function and more. It shortens one’s life expectancy.
Is obesity manifested by “distinguishing signs and symptoms?”
Yes, I think it is. Excess body weight is a visible sign that someone is obese. There are characteristic blood lipid and metabolic panels that indicate obesity, such as high low-density level cholesterol (LDL) and high trigylcerides. Obesity can affect one’s mobility, put excess strain on muscles and joints, thereby creating symptoms like knee pain and back pain. If obesity leads to cardiovascular disease, it can create symptoms such as shortness of breath, chest pain, strokes and heart attacks. Of course obesity can also lead to Type Two Diabetes and therefore it can lead to symptoms characteristic of diabetes, such as peeing at night, increased thirst, fatigue, neuropathy, double vision and more.
Finally, is what causes obesity a response “to environmental factors (as malnutrition, industrial hazards or climate), to specific infective agents ( as worms, bacteria or viruses), to inherent defects of the organism ( as genetic anomalies) or to combinations of these factors?” Here’s where it gets interesting.
Let’s first discuss environmental factors (such as malnutrition, industrial hazards or climate) in regard to what causes obesity:
In regard to industrialization and climate, today we are too sedentary. We are a computer-addicted culture. The computer is a huge part of our work lives and now a big part of our social lives, with networks such as Twitter and Facebook. This means a lot of sitting and physical inactivity, both of which can set the stage for obesity. A strong quote from a recent study on “sitting” as an independent risk factor for obesity (and other chronic ailments) is, “…recent epidemiologic evidence suggests that sitting time has deleterious cardiovascular and metabolic effects that are independent of whether adults meet physical activity guidelines. Evidence from “inactivity physiology” laboratory studies has identified unique mechanisms that are distinct from the biologic bases of exercising. ” This means that working out every day won’t matter if you are still sitting too much.
How else do we sit too much? Kids play video games instead of going outside to move around while playing, and as a society, we’re getting addicted to technology at a younger and younger age. We’re a culture that can order anything we want online and have it delivered directly to our homes, meaning we don’t even have to expend energy by going out shopping. This includes groceries. Think of how far we’ve come from our hunter/gatherer ancestors who had to go out into the woods, walk around for hours in search of their next meal, while carrying weapons. Now we can just surf the internet and press buttons for our food. We’ve even eliminated our walk to the post office, as now we can just press a button and send an email. While computers have made our lives more efficient and a lot easier in many ways, they haven’t helped our waist lines.
“The civilized man has built a coach, but has lost the use of his feet.” – Emerson
Our inability to unplug also impacts our sleep, and research shows that if we don’t sleep enough, we can gain weight. Not only that, but studies show that if we are sleep deprived, our bodies produce more cortisol ( responsible for abdominal fat), less leptin (the hormone that shuts off our appetites) and more grehlin, the hormone that tells us to eat more. The fact that we work later hours and have lights to ensure that we are able to work at night instead of sleeping could also be adding pounds to us. Our ancestors went to bed when the sun went down. They didn’t have the luxury of lights but at least they got a good night’s sleep.
Another modern industrial variable that plays a role in fat metabolism is temperature. Just turning up the HEAT in our homes slows weight loss and can potentially lead to obesity. I love my heater as much as the next guy, but it’s true. In a study published in Obesity Reviews it was shown that in the U.K, the average living room temperatures rose from 18.3°C (64.94°F) in 1978 to 19.1°C (66.38°F) in 2008, and the bedroom temperatures rose from 15.2°C (59.36°F) to 18.5°C (65.3°F). In America, the average bedroom temperature increased from 19.3°C (66.74°F) to 20.2°C (68.36°F). We like it hot. The study discusses how our bodies have evolved to be thermostats and if we constantly turn up the heat in cold environments, we don’t allow our bodies to expend energy to keep us warm. Time to bring shivering back? Maybe! The study also discussed “brown fat” and how it functions in the cold. While white fat is more of a storage house, brown fat is activated in cold weather to dissipate energy as heat (which burns calories!). Perhaps turning down the heat in the winter months would not only cut back on our heating bills but also cause us to lose weight? Along this same line of thinking, air conditioning is a culprit too. Some studies suggest that air conditioning inhibits the body’s ability to cool itself (another calorie-burning expenditure) and therefore costs us another fat-burning opportunity.
In reference to “climate,” it is also worth briefly mentioning endocrine modifiers, or agents in the environment that negatively impact our hormones. There’s been a lot of research on pesticides acting as endocrine modifiers thereby affecting many of our organs. BPA (bisphenol A), which is used to create plastic, food cans, containers, baby bottles and sippy cups) has been linked to obesity. BPA is a “hormone-mimic” and studies show that rodents exposed to BPA become obese. (The rodents also develop cancers of mammary and prostate glands, early onset of puberty, and Attention Deficit Disorder.) BPA is a widely acknowledge endocrine modifier that serves as a risk factor for obesity, but there are most likely other ones yet to be discovered. Along this line of thinking, one should consider the metabolites of prescription medication that are not broken down by our sewage systems ( They are not, as of yet, required to be) and end up in our water supplies. We don’t know yet how they are affecting our health. Perhaps those metabolites are risk factors for obesity, as well as other ailments.
Getting back to what causes obesity: Is obesity a response to malnutrition?
Usually when I think of malnutrition, I think of starving emaciated kids who do not have enough to eat. However malnutrition could also mean eating the types of of foods that are known to increase one’s risk for obesity or it could mean only having access to those types of food, which then becomes a “food climate” issue. For example, everyone knows an overabundance of fast food makes you fat and people who live in areas concentrated with fast food chains are, on average, larger than those people who do not live in fast food saturated areas. In a 2013 study conducted by the University of California at San Francisco and published in Diabetes Care, results show that healthier food environments are associated with lower obesity rates. This study also highlighted a relationship between income and obesity. The low obesity rates were only noted in the highest income groups and not the lowest income groups. Could this mean that obesity is a socioeconomic issue? It absolutely could, given the fact that fast and highly-processed foods are cheaper than many healthier foods, and because obesity is more prevalent in lower income groups.
What causes obesity- being poor?
Another study published in Health & Place shows that people living in poor neighborhoods have 2.5 times more exposure to fast food outlets than people in wealthier neighborhoods. Do fast food ventures target poor people? Perhaps. And poorer neighborhoods will always have more of a struggle with obesity as long as healthy food joints avoid them.
One should also consider other “neighborhood” elements that may contribute to poor neighborhoods having a bigger problem with obesity than wealthier ones. Is the crime rate too high for people to feel safe enough to go outside and exercise after work? Are there functional sidewalks and clean parks? Are there gyms? Is there a place to get any fresh fruits and vegetables? Often times you’ll find at least one of those elements to be lacking in poor neighborhoods.
Fast and processed foods are also addicting and research shows that they are scientifically designed to be addicting. The addictive qualities of contemporary foods could be fueling an obesity epidemic, however other research ( Food Addiction in Humans, The Journal of Nutrition, March, 2009) shows that any kind of food, tasty or not, can become addicting. That means I can’t entirely hold the “food scientists” responsible for the obesity epidemic. Still, the research clearly shows that people can and do become addicted to food, and that food addiction has many of the same characteristics as drug addiction.
Binge Eating disorder was in the proposed revision of the psychiatric manual DSM IV, and interestingly enough, Obesity was being considered as a psychiatric disorder for the latest version, DSM-V. Food intake is regulated by a reward-based system (Dopamine release), which is the same one involved in drug addiction. Sweet and fattening foods, like some alcoholic beverages, also cause the release of endogenous opioids, chemicals that make us feel really, really good. Further evidence shows that the dopamine-reward system can override all other homeostatic signals to stop eating. (This means that if someone is eating a particularly delicious food, his or her dopamine system can shut down all of their other signaling pathways that tell him/her to stop gorging themselves. )
Many studies, including a great one published in the Journal of Psychoactive drugs 2010 June edition, describes how sugar has been shown to have the same addictive properties as many recreational drugs. (This is why drug addiction programs might provide some guidance on how to handle obesity in the future.) There are so many other ridiculously complex neurological and endocrine pathways involved in the “food addiction” theory that are beyond the scope of this blog. But they’re out there if you are interested in researching them further. Of course, not everyone becomes addicted to food, but that should not be used to discredit the theory that a food addiction fuels obesity. Each of us have a very unique neuroendocrine and genetic profile– which ultimately means that we all differ in our ability to control what we eat. ( I’ll write more about food addiction in a subsequent blog on food cravings and how to control them.)
Also, our increasingly global dependence on meat (and particularly processed meat) could definitely be fueling an obesity epidemic, as well as destroying the quality of our food supply. To read more about this, check out a blog I wrote on meat and what the research shows.
On what causes obesity, does our social network matter?
If discussing the environmental and social determinants of obesity, it is also important to mention one’s social network. An individual’s social network, essentially who one lives with, who one socializes with, works with or who one regularly encounters, can influence whether or not that individual becomes obese. Social networks play a very influential role in many chronic diseases. In regard to obesity, a study published in the New England Journal of Medicine shows that if your friend becomes obese, your chance of becoming obese increases by 57%. We don’t need scientific research to understand how our social networks influence us. For example, if you live with your family and they order pizza and Chinese food every night for dinner, and you are expected to eat with them, you could gain weight. If you live with a roommate who is overweight and keeps fattening, unhealthy foods in the house, you will be more tempted to eat them yourself, and thus gain weight. Of course if you live at home with your family and your mom, dad, significant other or guardian serves a healthy meal every night, you’ll be less likely to gain weight. If your roommate works out at the gym and wants you to be his/her fitness partner, you’ll be less likely to become obese. If your boyfriend or girlfriend eats unhealthy and you eat together enough times, you might start to eat unhealthy. The influence of your social network is powerful, and in many ways, we become who we hang out with.
Now let’s talk about the last portion of the definition of a disease: inherent defects in and the genetics of an organism (human being, in this case). Are they what causes obesity?
There is evidence that dysregulation of cortisol metabolism leads to weight gain. Cortisol is commonly referred to as the “stress hormone,” because it increases in times of heightened stress. Being under a lot of stress can cause a person to eat more and cortisol, itself, is shown to cause the build up of abdominal fat, often considered the most dangerous kind of fat because of its association with heart disease. (This is also commonly referred to as the metabolic syndrome.)
In reference to genetics, there is evidence that shows a mother’s birth weight is the strongest indicator for childhood obesity. This should make people second guess themselves before they criticize, bully or exlude (Boy Scouts of America, I’m looking at you) a child for being overweight. In animal studies, it is shown that if a mother east high fat, high caloric foods, her offspring are more likely to be obese. Some obesity research has used Prader-Willi Syndrome (PWS), a genetic disorder of which one manifestation is overeating and obesity, as a model to identify specific genes that promote obesity. Using PWS as a model has helped scientists determine many neurological pathways that play a role in feeding/obesity, including the role of leptin (which is deficient in PWS), the hormone I discussed earlier in the blog in the section on sleep.
The “thrifty gene” hypothesis for obesity is also very popular in the public health literature. This hypothesis suggests that if a mother is under stress or calorie deprived while carrying a fetus, “thrifty genes” will be selected for in her offspring. These “thrifty genes” are ones that will be more efficient at the intake of food and fat storage. One can see how that might create a genetic profile that favors obesity. Recently the “thrifty gene” hypothesis has been challenged by the “drifty” gene hypothesis for obesity. The drifty gene theory suggests that certain genes that favor obesity, such as genes that are not efficient at metabolizing (oxidizing) high fat diets, are not selected for, and instead drift and wind up in the gene pool that way, almost randomly. No matter what hypothesis makes more sense to you, clearly genes play a role in the pathology of obesity.
What Causes Obesity: Viruses?
Getting back to the definition of a disease, could obesity be caused by “specific infective agents (as worms, bacteria, or viruses).” I find this area of research to be the most fascinating because viral and post-viral syndromes can have an infinite amount of manifestations, and we probably don’t know half of them. Humans a thousand years from now will probably look back at our knowledge of obesity and chuckle at our ignorance. Still, current research has shown that viruses can cause obesity. A large review published in the May0 Clinic Proceedings (2007) analyzed different viruses that cause obesity in animals and humans. A summary of the review follows: In animals, canine distemper virus, Rous-associated virus type 7, Borna disease virus, scrapie agent and SMAM-I are shown to cause obesity. SMAM-I is a virus from India that is also shown to cause obesity in humans by acting directly on the adipocytes, or fat cells. In humans, three adenoviruses have been associated with obesity. They are Ad36, Ad37 and Ad-5. Studies show that these viruses promote the maturation of mature adipocytes and promote the formation and storage of triglycerides. Ad-36 is the most studied human adenovirus and not only does it correlate with obesity in humans, but also in chickens, mice, rats and monkeys. More research is needed in this area, but I wouldn’t be surprised if 50 years from now a vaccine exists for obesity.
There are also studies that suggests that specific microbes in the gut may somehow lead to obesity, which could be the reason why taking probiotics may help someone lose weight. Certain gut bacteria are found in higher proportions in obese people than people of normal weight, but again, more research is required.
I’ve broken down the definition for “disease” to see if obesity qualified. Based on what I’ve written so far, I think it is fair to say that obesity can be labeled a disease. However, I am sure willpower, one’s level of laziness, motivation, one’s personal choices and one’s level of personal responsibility all play a significant role in the obesity epidemic. If they did not, then, based on the previously outlined potential reasons for obesity, it would be extremely difficult for an obese person to lose weight. Yet we all know obese people who have lost weight. How did they do it?
They can’t alter their genes or easily alter their neuroendocrine pathways. They can’t choose what viruses they are exposed to, and they have limited control over their food supply, social networks and environments. Surely some obese people lost weight via surgery, but I believe the majority who lost weight and keep it off most likely made changes in their personal choices about food and exercise, cultivated motivation to lose weight, and put in work towards living healthier lives.
What about the “medicalization” of obesity in order for the medical establishment to make money on it?
This is an interesting question. Currently, it is extremely difficult to get any insurance company to pay for a procedure or prescription related to obesity. Usually if a doctor sees a patient for “obesity,” they have to tell the insurance company that it was for some other comorbidity, such as Type 2 diabetes, in order to get reimbursed. Also, a 2009 survey published in Obesity shows that two-thirds of family physicians find dealing with obese patients to be frustrating. There are other surveys that show primary care doctors do not have the time nor know how to counsel patients about obesity. Perhaps labeling obesity a disease will cause doctors to address it more seriously, in a less stigmatizing manner, and perhaps insurance companies will be required to pay for obesity drugs and treatments.
The other question is did the AMA label obesity a disease to benefit pharmaceutical companies that would start making money on drugs targeting obesity? Since insurance companies rarely pay for obesity treatments, a pharmaceutical company specializing in obesity drugs would have a tough time selling their product. Coincidentally, VIVUS recently released the obesity drug, Qsymia, which lost 53.6 million dollars in 2013, because VIVUS couldn’t sell it. Perhaps if obesity is more “medicalized,” and the norm becomes treating obesity with drugs, pharmaceutical companies can start selling their drugs and there is no doubt they will make a lot, a lot, a lot, and a lot of money.
I’m not picking on the pharmaceutical companies this time, because the supplement industry is already banking off of weight loss pills, products, patches, and you name it, it’s out there. In fact, one of those companies was just busted for adding pesticides into their supplements. My 2 cents: Weight loss supplements are a huge farce and marketing scheme. They often contain contaminants. They can be made in someone’s basement and then put on the market without being tested and without any regulation at all. They don’t work. Don’t be stupid. Save your money.
Obesity may also be the result of another medical illness or ailment, one that is diagnosed or has yet to be diagnosed, so in that sense, obesity may already be “medicalized.” Medical illnesses that can cause obesity include Polycystic Ovarian Syndrome, certain genetic illnesses, hormonal imbalances, Cushings disease, Hypothyroidism, Autoimmune diseases and more. Also, obesity can be the result of medication, such as certain birth controls and many psychiatric drugs.
In summary, below is a chart I made to visualize what causes obesity. I included “Unknown causes,” because I am sure we haven’t discovered all of the causes for obesity. More will be unveiled with time. The take-home point of the chart ( and this blog) is that obesity is a phenomenon caused by many factors. Therefore the approach to obesity needs to be holistic in nature, or one that can analyze and address all of those factors, and also an approach that addresses how those factors interact with one another to make the obesity problem even worse.
When you are done reading this, check out an essay I wrote here: My Long First Date With Death.