Overweight and Obesity Epidemic in America – Part IV:

Suggested Citation: Garko, M.G. (2011, January). Overweight and obesity epidemic in America – Part IV:  What risk factors and causes are and why it is important to know about them. Retrieved (insert month, day year), from www.letstalknutrition.com


Overweight and Obesity Epidemic in America – Part IV: What Risk Factors and Causes Are and Why It Is Important To Know About Them

 Michael G. Garko, Ph.D.
Host – Let’s Talk Nutrition


“Life is not living, but living in health” (Marcus Valerius Martialis, 1st century Roman poet).It might appear to some that the majority of the population in the United States is living in health because of the (1) considerable public and private sector resources devoted to educating the general population about healthy living, (2) extraordinary amount of dollars spent on advertising and marketing healthy living and (3) advanced medical system serving the country.

However, when it comes to living in health in the United States, things are not what they seem. For example, according to the Centers for Disease Control and Prevention (2010), chronic diseases (e.g., heart disease, stroke, cancer, diabetes & arthritis) are among the most common, costly and preventable of all health issues facing the country and constitute the leading causes of death and disability in America.

Specifically, 70% of deaths among Americans stem from chronic diseases, with more than 50% of all deaths caused annually by heart disease, cancer and stroke.  Back in 2005, 133 million Americans, nearly 50% of adults, suffered from at least one chronic illness. Approximately one-fourth of those beset with chronic conditions are limited in one or more daily activities.Arthritis continues as the most common cause of disability in the United States, with almost 19 million arthritic Americans reporting activity limitations. Diabetes remains the leading cause of kidney failure, non-traumatic lower-extremity amputations and blindness among adults 20-74 years of age (Centers for Disease Control and Prevention, 2010).

Making matters worse is the overweight and obesity epidemic in America, which has emerged as being among the most serious public health threats to American adults and children in the 21st century. An estimated 34.2% of American adults 20 years of age and older are overweight and 33.8% are obese (Ogden & Carroll, 2010). Not only is obesity epidemic a threat to decrease life expectancy in the United States by as much as five years but it contributes in a significant way to the condition of chronic diseases and associated illnesses. For example, a large body of scientific research has established obesity to be associated with coronary heart disease, stroke, high blood pressure, high cholesterol, type 2 diabetes, gallbladder disease, osteoarthritis, respiratory problems, cancer (e.g., endometrial, breast, prostate and colon cancer), insulin resistance and psychological problems, among other health conditions (see U.S. Department of Health and Human Services, 2010).

Living in health requires a considerable measure of initiative and insight supported by information. In that regard, this January, 2011 issue of Health and Wellbeing Monthly is intended to inform readers on the concepts of risk factors and causes within the context of the overweight and obesity epidemic. Specifically, this month’s article is designed to serve as a foundation for upcoming articles in which specific causes and risk factors responsible for the overweight and obesity epidemic will be discussed and proposed lifestyle and nutrition strategies found in the literature to help curb the tide of the epidemic will be outlined.

The Difference Between Risk Factors and Causes

Risk factors can be defined as variables possessing the potential to increase the likelihood of developing a particular disease or health condition (e.g., overweight or obesity). They are linked to a disease or health condition by means of a statistical association or correlation. The stronger the statistical association is the stronger the inference that can be made about a particular factor putting a person at risk for becoming obese.  

It is important to understand that while a particular risk factor or set of risk factors increases the likelihood of becoming overweight or obese, this does not mean that there is a certainty suffering from either condition (see Black, 1993).

In contrast to a risk factor, a cause is “that which produces or effects a result; that from which anything proceeds, and without which it would not exist” (Webster’s Online Dictionary, 2010). Thus, causes of obesity are definitive in producing it.

Correlational vs. causal. A common misunderstanding is that risk factors for obesity are causes of it. As it was pointed out, the relationship between risk factors and obesity is correlational in nature. Their connection to obesity is not causal in nature. Risk factors represent a necessary condition for the development of obesity. Causes of obesity represent a sufficient condition. In other words, a particular risk factor contributes to obesity, while a cause of obesity ensures it. For example, age is recognized as a risk factor contributing to the development of obesity but it has not been established scientifically as causing obesity independent of any other factor.

Risk factors serve as the scientific basis for the causes of obesity and can become established causes of it. In order for a risk factor to be recognized as a cause for obesity (or any health condition or disease for that matter), sufficient scientific evidence must exist to show that it increases the overall number of cases of obesity or makes it develop sooner than it otherwise would (U.S. Department of Health and Human Services, 2004).

In sum, unless a risk factor has been established through rigorous scientific studies to bring about obesity independent of other factors, then it cannot be considered to be a cause of it. Risk factors for obesity put people at some level of statistical risk for developing it but they do not cause it. All recognized causes of obesity are risk factors but not all risk factors are causes of obesity.

Making the list as a risk factor. Although they are not causal in nature, risk factors play a profound role in the development of obesity. Consequently, they should not be taken lightly. Yet, they should not be put on the list of recognized risk factors for obesity until they have met certain criteria. Although set within the context of coronary heart disease, Black’s (1993) six criteria for a variable to be considered a legitimate and meaningful risk factor can be adapted to obesity.

First, the statistical association between the risk factor and obesity must be strong. That is, according to Black (1993), “the presence of the factor should at least double the risk of disease” (p.25).

Second, the statistical association should be consistent in that the “risk factor should produce disease regardless of gender, age, or race and the association should be present in all or most of the studies in which it has been evaluated (Black, 1993,  p. 25).

Third, the statistical relationship between the risk factor and obesity must make biological sense. Black (1993) contends that “unless such a relationship is biologically plausible, the statistical association may have little meaning” (p. 25). It is often the case in science that statistically significant findings are of no real practical importance.

Fourth, the health impact of risk factors should be able to be demonstrated experimentally in a laboratory. Black (1993) admits that this criterion is difficult to satisfy, especially since it is not always feasible or ethical to subject humans to experiments.

Fifth, treatment that can favorably modify the impact of the risk factor should reduce the incidence of the disease. Black (1993 recognizes that this particular criterion has been satisfied for some but not all of the recognized risk factors.

Lastly, the risk factor must make an independent contribution to increasing the likelihood of developing the disease. Again, Black (1993) admits that some proposed risk factors simply occur together with other more legitimate risk factors.

Modifiable & Non-modifiable Risk Factors and Causes

Risk factors and causes can be classified as being modifiable and non-modifiable, a frequently used approach. Non-modifiable risk factors are genetically determined traits (e.g., age, gender & race-ethnicity). Modifiable risk factors involve lifestyle variables (e.g., high stress levels, lack of exercise, poor nutrition, etc.) and acquired conditions (e.g., elevated blood pressure, insulin resistance, etc.). Lifestyle and acquired conditions are assumed in the literature to be changeable and ideally subject to improvement and prevention, while heredity based factors are viewed as fixed and unchangeable. 

Multi-factorial and Interactional.

Obesity is not associated with or caused by a single variable. Rather, obesity is multi-factorial. The research on obesity provides convincing evidence that it stems from a complex of interacting traits, acquired conditions and lifestyle variables that implicate various environmental, behavioral, psychological, physiological, social and genetic factors.

Some risk factors are described in the literature as being independent (e.g., overeating) because they have the potential to bring about obesity single-handedly. However, risk factors and causes can and most often interact and work together with one another to create a greater likelihood of becoming obese and produce a greater deleterious impact on a person’s health. It stands to reason that the more risk factors and causes an individual possesses for obesity the greater the chances of that person developing and dying from it.


Perhaps Marcus Valerius Martialis’ quote about living in health should be modified to read, “Life is not living, but living in health by taking personal responsibility.”  If obesity is to be prevented, then health consumers need to assume responsibility in not becoming obese.  An important step to take in that direction is first to have a basic understanding of what risk factors and causes are and then to learn about which risk factors and causes are responsible for overweight and obesity.

This month’s issue of Health and Wellbeing Monthly focused on what risk factors and causes are and the difference between them. In the upcoming issue in the series on the overweight and obesity epidemic in America, readers will learn about specific modifiable and non-modifiable factors putting people at risk for becoming overweight and or obese. Knowing about these various risk factors and causes can help individuals assess (with the help of a healthcare professional) their likelihood of becoming overweight or obese and provide them with some guidance in eliminating at least reducing the impact of those risk factors and causes, all of which can lead to better overall health and disease prevention.  


Black, W.K. (1992). Cardiovascular risk factors. In B. L. Zaret, M. M. Moser & L. S. Cohen (Eds.), Yale university school of medicine heart book (pp. 23-35). New York: Hearst Press. 

U.S.Department of Health and Human Services (2004). The health consequences of smoking: A report of the Surgeon General. Washington, DC: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health.

U.S.Department of Health and Human Services, 2010). The surgeon general’s vision for a healthy and fit nation. Rockville, MD: U.S. Department of Health and Human Services, Office of the Surgeon General.

Webster’s Online Dictionary (2009). Cause. Retrieved December 1, 2010, from http://www.webster-dictionary.org/definition/cause


Suggested Citation: Garko, M.G. (2011, January). Overweight and obesity epidemic in America – Part IV:  What risk factors and causes are and why it is important to know about them. Retrieved (insert month, day year), from www.letstalknutrition.com