Sunday, July 7, 2013

Should We See Obesity as a Disease?

Recently, the American Medical Association (AMA) recognized that obesity is a disease. This decision was actually the exact opposite of the recommendations made by the AMA's own investigating committee. What was the AMA's reasoning? To try and stop the growing epidemic of obesity by changing the way doctors and insurance companies view those with a Body Mass Index (BMI) of more than 30.

For sure, obesity is starting to get out of hand. The World Health Organization (WHO) estimates that obesity affects over 500 million adults and 40 million children under the age 5 worldwide. This represents about 10 percent of the population. The WHO also believes that obesity is now the fifth leading cause of death (globally) and is strongly associated with degenerative diseases like heart disease, diabetes, and some cancers. (1)

The age-adjusted rate of obesity in the US (in 2008).

Like many other bloggers, I'm happy to hear that the medical community is taking obesity more seriously, but am also conflicted about the decision to see obesity as a disease.

Obesity as a Disease
Let me start with the most obvious question: Is obesity a disease? This question can be answered by looking at the definition of disease:
Disease (n): a disordered or incorrectly functioning organ, part, structure, or system of the body resulting from the effect of genetic or developmental errors, infection, poisons, nutritional deficiency or imbalance, toxicity, or unfavorable environmental factors; illness; sickness; ailment. 
By this definition, the AMA is correct in seeing obesity as a disease, as excessive amounts of body fat can cause health problems elsewhere in the body.

For instance, researchers are finding out that body fat cells don't just store energy, they collectively act as an endocrine organ that produce both inflammatory and anti-inflammatory chemical messengers (known as cytokines). (2) The pro-inflammatory cytokines include TNF-aIL-1IL-6IL-18, and leptin. If a person has too much body fat, too much of these pro-inflammatory chemical messengers can cause a number of problems throughout the body, including rheumatoid arthritis, (3) asthma, (4) systemic inflammation, (5) diabetes, (6) atherosclerosis, (7) depression, (8) Alzheimer's Disease, (9) Celiac's Disease, (10) and certain cancers (11)

Excess body fat can also contribute to chronic stress by locally activating too much of the inactive form of the stress hormone cortisol. (12) As I have talked about before, excess cortisol can cause energy (e.g., triglycerides, glucose) to be funneled into visceral fat (that's the fat that surrounds your internal organs), trapping it there and slowly increasing a person's waistline and eventually producing a potbelly. (13) And excess visceral fat is more associated with poor health than excess subcutaneous fat. (14)

But here's the kicker: While it's clear that excess body fat conforms to the definition of a disease, a normal amount of body fat does not.

This raises another question: How did Americans start putting on so much body fat that they started developing the disease of obesity?

The Recent Rise of Obesity
Although obesity seems normal or common in the US today, just 100 years ago it was almost non-existent. (15) I say almost because obesity has affected a very small percentage of humans for hundreds (probably thousands) of years. (16)

In fact, by the end of the 19th century, most people in the US were closer to being underweight (under a BMI of 18.5) than overweight. (17) The graph below shows the BMI of American 18-year-olds from 1850s to the 1980s. You'll notice that in the 1800s, the average BMI was on the low end of the normal weight range (which is a BMI from 18.5 to 24.9).

BMI values and weight of 18-year-old American men. Data pertains to whites. WPC= West Point Cadets; SC = students attending The Citadel Military Academy in Charleston, SC; US = national sample. The weights pertain to a man who is 70 inches (177.8 cm) tall. (Source)

Then, starting around the end of the 19th century, the number of people in the US who were overweight (which is defined as a BMI of 25 or greater) started to slowly increase through to the 1980s. By that decade, 14% of those who were overweight were classified as obese (those with a BMI of 30 or greater).

After the 1980s, something very peculiar happened. Although it took about 80 years for obesity rates to reach 14% by 1980, after 1980 obesity rates more than doubled in only 30 years, reaching 33% by 2010. (18)

What's more interesting about the rise of obesity in the 20th century is that it didn't affect all human populations. Other Westernized countries took much longer to start to develop a problem with obesity. And there were several non-industrial human populations that did not suffer from obesity or excessive body weight at all. These populations include the Kitivans, Masai, Kung!, and Turkana. (19) (Unfortunately, many of these populations started to develop obesity [and many other degenerative diseases] after adopting a more Western diet and lifestyle.)

This is an overview of the overall health of non-industrial populations as they transition from their traditional diets to a more Westernized one. (Source)

Obesity as a Symptom of an Industrialized Society
So, why did more Americans suddenly start becoming overweight at the beginning of the 20th century? And why was there a sharp increase in the number of excessively overweight (or obese) people after the 1980s? What changed?

I believe that the Industrial Revolution radically changed the American diet, lifestyle, and culture. These changes were further expanded around the 1980s.

Shortly after the Industrial Revolution, the traditional nutrient-dense American diet was slowly replaced by highly-refined, nutrient devoid, toxin-filled foods. These new foods lacked the nutrients necessary to help the human body operate correctly and prevent disease. In fact, the deficiency diseases that quickly followed the introduction of new industrially-produced foods (e.g., beriberi, ricketsscurvy) alerted the medical community that there were essential nutrients in fresh whole foods that were lost by careless processing, leading to the discovery of vitamins (and the concept of nutrient enrichment).

The Industrial Revolution also increased the number of people who were sedentary. The car, radio, and TV each encouraged Americans to sit still for longer periods of time.

Finally, the American culture became a source of chronic stress, with its emphasis on constant hard work and creating extreme forms of individualism that break away from traditional support structures like family and community.

This deviation with traditional diet, lifestyle, and culture produced chronic nutrient deficiencies, inactivity, and stress. Together, these changes started making people sick, with the brain's inability to regulate calorie intake and body weight (which eventually results in obesity) as a visual display of this sickness.

Since this disconnection with tradition was small at the beginning of the 20th century, it produced smaller percentages of people who were obese. But, by the 1980s, there were radical changes to the American diet, lifestyle, and culture that started to accelerate the number of people suffering from obesity, producing the current obesity epidemic.

The American diet was further changed by the rising popularity of nutritionally-poor fast foods, sugar drinks, and low-fat/low-cholesterol foods. The American lifestyle become more sedentary with the prevalence of the desk job and computer usage. And the American culture was made increasingly stressful and disconnected by a demanding business culture.

But these changes didn't just make people fatter, it also accelerated the rise of other degenerative diseases like diabetes, heart disease, and cancer. (20) I believe that is why obesity often appears together with these diseases in what is known as Metabolic Syndrome X. (21)

Can Obesity be Cured?
Obesity is definitely a disease, but developing obesity is extremely difficult if you are healthy. In reality, obesity is a symptom of fundamental changes to the American diet, lifestyle and culture experienced after the dawn of the Industrial Revolution.

However, because the medical community doesn't seem to see it that way, those who suffer from obesity will likely just be prescribed drugs to "fix" their disease. Unfortunately, drugs don't usually cure people, they manage symptoms (essentially making you comfortably sick). So even if doctors and insurance companies change their attitude towards obesity, it likely won't fix the underlying cause of obesity, which is improper calorie management by the brain (which is an unconscious process; if you find yourself overeating, then you've got bigger problems that consciously starving yourself will not fix).

Of course, researchers and bloggers have already largely found the causes and possible cures for obesity (although you are unlikely to hear about them from your doctor). But I will save that stuff for future blog posts.  

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