Can Obesity Be Contagious?

can obesity be contagious

Story at-a-glance -

  • Obesity is a deadly health condition, associated with heart disease, diabetes, depression, cancer and premature death
  • Using data from military bases, researchers demonstrate your social network has a significant impact on your risk of becoming overweight or obese
  • Other lifestyle choices that impact weight management include sleep, hydration, fuel source and exercise and movement

By Dr. Mercola

Obesity is deadly. Today it is growing at epidemic proportions and researchers find it may spread through communities. According to the U.S. Centers for Disease Control and Prevention (CDC), nearly 30 percent of adult Americans are obese.1 By comparison, in 1989 when the CDC began collecting data, no state reported obesity rates over 14 percent.2 By 2010 only one state reported obesity rates below 19 percent.

The rising rates of obesity and challenges with weight management have been topics of discussion for at least 30 years. A multibillion-dollar industry emerged to address the topic and offer options to reduce your weight. Pills, surgeries, books, exercise programs and spas are just a few of the choices furnished by an industry primarily interested in financial gain.

A number of identified factors have contributed to rising rates of obesity, including a sedentary lifestyle, poor dietary choices and limited access to health care.3 A combination of poor choices and poor information has created circumstances where 1 in every 5 deaths in the U.S. is associated with the consequences of obesity.4

Researchers have documented evidence that social networks in your immediate geographical neighborhood may also play a part in your struggle with weight management.5

Study Demonstrates the Power of Social Networks

The question that inspired the study was based on observations of physicians from Yale University and University of California San Diego who found a variety of behaviors appeared to spread through social networks. They first mapped relationships between friends and family in the Framingham Heart Study, not unexpectedly finding that smoking, happiness and divorce appeared to spread through communities of individuals as if contagious.6

Obesity was one of the first health factors the team identified as consistent across a group of socially connected individuals. In 2007, the team reported that if a person's spouse, sibling or friend became obese, the individual's chance of also becoming obese increased between 37 and 57 percent.

To understand if this data represented the concept of "birds of a feather flock together," or if individuals truly had a greater propensity of gaining weight when inserted into a population of overweight individuals, it was necessary to find a population of people who were not obese and assign them social networks with varying degrees of obesity. By assigning servicemen and women to bases across the country, the military had effectively met this criteria.

Two economists continued the investigation into whether social networks had a unique but powerful impact on the probability an individual would become obese when their immediate social network was also obese. Ashlesha Datar, Ph.D., from the University of Southern California (USC) and Nancy Nicosia, Ph.D., from Rand Corporation, a nonprofit research organization,7 gathered data from over 1,100 teens and 1,300 parents.

Of these, nearly 25 percent of the teens and 75 percent of the adults were overweight or obese. Indeed, their probability of experiencing weight challenges rose if they had been sent to a county base where obesity was the norm. For every 1 percentage point rise in the obesity rate of the county, the odds a teen would be overweight rose to nearly 6 percent; the odds for parents rose to nearly 5 percent.8

Degree of Contact Also a Contributing Factor

The economists also found weight status was tied strongly to those who had a greater degree of exposure to the surrounding community. In other words, the relationship between body mass index and the county obesity rate was stronger in teens who lived on or near an Army base for more than two years as compared to those teens who were new arrivals. The researchers also found the link was stronger for families who lived off-base than for those who lived on the military base. Datar explained:9

"Living in a community where obesity is more of the norm than not can influence what is socially acceptable in terms of eating and exercise behaviors and body size. If more people around you are obese then that may increase your own chances of becoming obese."

The study evaluated military-based families in counties where the obesity rate ranged from 21 percent (El Paso County, Colorado) to 38 percent (Vernon County, Louisiana).10 While moving to a county with a high obesity rate increased the risk of becoming obese, the researchers also found the opposite was true. When families moved to El Paso County, the risk of becoming obese declined by 29 percent for adults and 23 percent for children.

Health Habits May Spread Through Your Community

The results of the feature study support information and research from other psychological and medical studies that offer data demonstrating your behavior is highly influenced by your environment and the individuals with whom you associate.

Researchers from Harvard Medical School and the University of California found that if a person becomes obese, those who are close to them, no matter the geographical distance, have a greater chance of also becoming overweight or obese.11 Between same sex friends, the increased risk was as high as 77 percent. The researchers commented:12

"Network phenomena appear to be relevant to the biologic and behavioral trait of obesity, and obesity appears to spread through social ties. These findings have implications for clinical and public health interventions."

Another study evaluating the social norms on eating behaviors and patterns also concluded that social influences were pervasive and powerful, playing a role in the development of obesity.13 Research has demonstrated it isn't only what is eaten that is influenced by peer relationships, but also how much.14 People tend to eat less when their dining companion eats smaller portions and feel free to eat as much as they like when dining with a generous eater.

Lenny Vartanian​, Ph.D., professor of health, clinical and counseling psychology from the University of New South Wales, Australia, led a meta-analysis review of 38 studies and found modeling had a significant effect on the amount of food an individual ate.15 Vartanian explained the results, saying:16

"I'm not downplaying the importance of portion size, but the magnitude of the effect found that [social modelling] is about twice the size of the effect you get from portion size."

Social networks also have an influence on exercise habits, as researchers demonstrate that the habits of close friends have an impact on your own habits.17 Further data demonstrates a relationship between habits and relationships in a Gallup Poll that found smokers were twice as likely as nonsmokers to have friends and family who smoked.18

Social Contact May Influence Behavior but Nutrition Continues to Drive Obesity

According to science journalist and author Gary Taubes, writing in the BMJ, sugar contributes far more than excess calories in the epidemic rise of diabetes and obesity.19 In his editorial he calls for science to take a strong look at the way in which sugars are metabolized differently from other carbohydrates, increasing your risk for inflammation and changing you risk profile for diabetes and obesity to a greater degree than excess calories alone would indicate.

Until recently, fats and energy balance have been the focus of weight management experts and scientists as the explanation for increasing waistlines around the world. However, despite the best efforts of doctors, these twin health disasters have continued to grow unchecked. Taubes suggests this is likely since our understanding of how sugar affects health is fundamentally flawed and the effect of sugar may be independent of calories. He says:20

"If it is true, though, it changes how we must communicate the dangers of sugar consumption ... but we don't know if the level recommended is safe for everyone. It could be that for people who have obesity or diabetes, or both, even a little is too much. And the ubiquity of sugar rich products may make it difficult for many people to maintain a healthy level of sugar consumption."

Taubes' comments are supported by numerous studies linking refined sugar and fructose to cancer, immune dysfunction, weight gain and heart disease. The sugar industry was well aware of the health conditions triggered by the product but, taking the same path as the tobacco industry, hid the information in an effort to protect sales.21

Historical documents show the industry spent decades manipulating documentation to lay the blame for obesity and disease on the doorstep of fats while sidestepping their own responsibility. Researchers found:22

"The sugar industry did not disclose evidence of harm from animal studies that would have (1) strengthened the case that the CHD risk of sucrose is greater than starch and (2) caused sucrose to be scrutinized as a potential carcinogen. The influence of the gut microbiota in the differential effects of sucrose and starch on blood lipids, as well as the influence of carbohydrate quality on beta-glucuronidase and cancer activity, deserve further scrutiny."

In response, the Sugar Association claimed23 "We know that sugar consumed in moderation is part of a balanced lifestyle …" But how balanced is a lifestyle where the majority of foods produced by manufacturers contains at least one type of sweetener and research has demonstrated that for many sugar is as addictive as cocaine,24 and your body's response to sugar advances the growth of cancer and triggers cardiovascular disease, insulin resistance and nonalcoholic fatty liver disease?25

Lifestyle Choices Affecting Your Risk of Obesity

Eating sugar-laden products is just one nutritional choice that may increase your risk. Aside from nutritional and social network risk factors, the following lifestyle choices may also influence your weight management efforts.

Fuel source: Eating fat for fuel instead of carbohydrates is one of the smartest choices you can make to not only manage your weight, but also take control of your health. There are significant benefits to this strategy, from reducing overall inflammation to reducing your risk of cancer and managing your weight. Find more about the advantages of a ketogenic diet when your body burns healthy fats for fuel in my previous article, "Ketogenic Diet for Optimal Health."

Hydration: Your body requires adequate hydration to rid waste products through your kidneys, maintain blood circulation and keep your brain functioning optimally. Before feeling thirsty, you will first experience hunger. According to Alissa Rumsey, registered dietitian from the American Academy of Nutrition and Dietetics,26 "Mild dehydration is often masked as feelings of hunger, when really your body just needs fluids."

Discover the effects of dehydration on your brain and thinking and how to assess your hydration levels in my previous article, "How Dehydration Affects Your Brain Function."

Quality sleep: Sleep deprivation takes a terrible toll on many who live a fast-paced, never-stop lifestyle. Unfortunately, the cost may be an increased risk of Type 2 diabetes, reduced brain function and an increased risk of obesity. Discover more in my previous article, "The Steep Cost of Sleep Deprivation."

Exercise and movement: These are two distinct factors. Exercise occurs when your heart and breathing rate increase and your body may begin sweating, such as when swimming, running, biking or rowing. Movement is a function of getting up out of your chair and walking or stretching. Both are necessary factors and have profoundly powerful benefits to your health and longevity.

To get the most benefit consider using high-intensity interval training, the Nitric Oxide Dump a couple of times each day, and getting out of your chair and avoiding sitting for more than three hours per day.

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