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Why do we get fat?

Jade Teta & Keoni Teta

How do we explain the huge jump in obesity in the last thirty years? Did we all start eating more and exercising less? Did everyone on the planet suddenly undergo a simultaneous genetic mutation?

We all have an opinion about obesity. Some people think it’s about laziness. Others think it is about poor genetics. But almost everyone believes it is a simple matter of exercising more and eating less.

Treating the human body as a simplistic piece of machinery that conforms to simple mathematic equations has always seemed shortsighted to us. Even the performance of an automobile engine, which is not nearly as complex as the human body, is known to be impacted by pressure in the tires, the grade of fuel, or the last time you had an oil change.


Is it really eating more and exercising less?

There is no doubt diet and exercise play a very strong role in obesity, but the calorie model leaves more questions than answers. Many people blame too many calories and especially high fat diets as the major reason there is a problem. But the data doesn’t support this as strongly as you may think.

A February 6th 2004 review in Morbidity and Mortality Weekly Report (Volume 53 # 4) showed calorie consumption did not change much and fat intake actually decreased between 1971 and 2000. Yet during this time obesity rates skyrocketed from 14.5% to 30.9%.

Another report in October 2008 published in the journal Obesity (Volume 16 # 10) showed dietary carbohydrate intake did increase significantly during this time hinting there may be more than a quantity issue when it comes to food. Not surprisingly this same study showed adult levels of physical activity also declined.

But, even physical activity levels may not be as big a factor as once thought. A study by Dr. Edward Melanson published in the April 2009 Exercise and Sport Science Reviews April 2009 showed exercise had little metabolic advantage. This study looked almost exclusively at moderate intensity aerobic exercise like jogging, biking, or swimming.

However, there are some hints more intense exercise may have a different outcome. In March 2002, Schuenke et al. showed a circuit resistance-training program utilizing heavy weights, short rest periods, and lasting only thirty-one minutes was able to generate a significant metabolic effect that persisted for 48 hours.

This was published in the European Journal of Applied Physiology. The results showed metabolism 24 hours and 48 hours after the exercise session was increased by 21% and 19% respectively. The researchers pointed out that for a typical 180-pound individual “This equates to 773 calories expended post exercise”.

To add to this picture, an October 27th 2009 article published online in the journal Obesity Reviews showed children are not exercising any less than they did in the past. From 1993 to 2005 the percent of vigorously active children dropped only slightly from 65.8% to 64.1% leading the researchers to conclude “Reduced physical activity is not likely the major explanation of the recent increase in obesity among US adolescents.”

Genes, lifestyle, hormones, and epigenetics

Are people fat because of their genes or are they fat because their genes are in the wrong environment? This is one of the classic arguments of all time, nature vs. nurture. Are we destined to become what our genes say, or does our environment shape us?

Many people perceive the DNA of a cell as the cells brain. They think without the genes, the cell will die. But if the genes are removed from a cell, the cell goes right on living. It breathes, it makes energy, it gets rid of waste, and it carries on like any other normal cell.

This happens because the genes are not the brain of the cell but rather more like your local auto-parts store. When a cell “part” or protein wears down and needs to be replaced, the genes hold the instructions for making a new part.

The cell membrane acts more like a cells brain. A cell membrane covers every cell in your body. The surface of the membrane holds thousands of receptors that interact with the hormonal signaling molecules of the body. If you remove these receptors on the cell membrane the cell will die.

This relationship has been described by one of the most popular molecular biologists in the country, Dr. Bruce Lipton. Environmental signals can control what genes are turned on or off. This is called epigenetics and is the science of the regulation of gene expression.

Hormones bind to receptors on cell membranes setting into motion signals that instruct the cell how to behave. It is lifestyle choices that ultimately determine the hormonal signals sent.

Food, exercise, thoughts, behaviors, light, sound, and other choices act as information for the body that sets your hormonal software in motion. While you may have a gene encoding a defective part, like say the gene for breast cancer, it is the hormones produced by your life choices that determine how that gene will ever be expressed.

The most compelling example of the environment versus genes argument can be seen in the Pima Indians. In the Journal Diabetes Care in 2006 Leslie Schulz PHD looked at two different groups of Pima Indians who were genetically Identical but lived in different environmental extremes.

One group of Pima lives in the Arizona desert and has the highest incidence of obesity and diabetes in the modern world. The other group live in a remote region of the Sierra Madre in Mexico and enjoy robust health and exceedingly low rates of obesity.

These two groups of Indians are 100% genetically identical. They were separated by a migration in their society 2,000 years ago. The Mexican Pima live the same life they have lived for generations while the US Pima have been assaulted with the western environment and lifestyle.

Of the two groups of Indians, the US Pima take in the same amount of calories and eat the same proportion of calories from fat and protein. The major difference was in lifestyle and type of carbohydrate and fat consumed. The Mexican Pima exercise more, eat less refined sugars, sleep more, and live a life more in line with their ancestral genes.

The calorie model and “genes are everything” dogma cannot predict this vast discrepancy in health and fitness between these identical groups of people. The diseases of the US Pima are not a result of increased caloric consumption or “bad” genes, but a result of poor hormonal metabolism induced by improper lifestyle and food choices.

Obesogens, POPS, and endocrine disruptors

A study published in the April 13th, 2009 issue of the journal PLOS ONE has shown environmental toxins may be a significant factor in obesity. Persistent organic pollutants (POPS) is the term researchers use to describe chemical toxins found in ground water and soil that have been shown to concentrate in plants and animals, move up the food chain, and be consumed by humans.

Research published in Diabetes Care (November 2006) showed a positive association between blood levels of POPS and severe metabolic dysfunction. One particularly prevalent toxin is the herbicide atrazine. Atrazine is sprayed on crops, especially corn, and is found in high concentrations across the US with the highest levels in the Midwest and Southeast. This is also the area of our country with the highest prevalence of obesity. Introduction and use of atracine starting in the early 1960′s closely matches the rise of obesity in many areas of our country.

Atracine is an example of an obesogen and acts as a hormone disruptor. Trace amounts of this chemical result in negative and persistent alterations in insulin and leptin levels, two hormones that impact fat storage and appetite respectively. Rats fed trace amounts of this chemical develop metabolic derangement and resistance to fat loss.

Final Thoughts

While it is important not to draw exaggerated conclusions from the studies presented here, it is necessary to realize there is more to obesity than meets the eye. There is little doubt diet and exercise play the most important role in obesity management. But it is clear the simple formulas we have been applying to this problem may be missing the bigger picture.

Obesity seems to be a problem of multiple factors; most important of which seem to be disrupted cell signaling coming from the wrong environmental inputs. Given the current practices of eat less and exercise more may not provide the benefit we once believed, it may be time to look at other tools. Quality of food over quantity of food, intensity of exercise not just duration, and chemical compounds in the environment should all be examined.

Obviously, there are many other factors contributing to obesity. But it is becoming clear obesity and weight loss are not simply a matter of calories. The dogmatic adherence to this belief may be one of the biggest obstacles to taking on this challenge. Given obesity is the single biggest health challenge of this century, it is wise to take a wider view and institute more holistic treatments. This may be the only way to make a difference.