Is obesity contagious? Before you grab me by my shoulders and begin shaking me hard while shouting in my face “what kind of question is that?” hear me out. I am not referring to the generic definition of contagious and suggesting that if you drink from the same glass as an obese person that you will begin to gain weight. Nor am I suggesting that a preventive inoculation can be administered at some time of the year that might be referred to as “obese season.” I am not saying that at all, so please, take your hands off my shoulders.
Findings published in the New England Journal of Medicine that answer the question, “is obesity contagious?” cite the contagion as a social experience. Not bacterial or viral, but something shared through interpersonal relationships.
Is Obesity Contagious?
Social contagion occurs when people follow the example of friends or family and gain and lose weight along with them. Given this definition, then, we might see how obesity is contagious. Statistics showed that the chances of a person becoming obese increased by 57% if they had a friend who became obese, 40% if they had a sibling who became obese, and 37% if they had a spouse who became obese. In addition, it was discovered that mutual friends more than tripled the risk to each other. If one of two mutual friends were to become obese, the chance for the other to do the same went up to 171%.
Not only that, but it was also found that a person’s chances of becoming obese were influenced by family and friends even if hundreds of miles separated them. An example as to how this might happen could be traveling on a holiday visit. Upon arrival, one person notes that another has become much heavier and emulates the weight gain he returns home. The likelihood for shared weight gain was greatest among people of the same sex.
This presents a good case for the social contagion of obesity. And the phenomenon also works in reverse. If a friend or family member loses weight, a person might also emulate that behavior and also lose weight.
The Obesity We Share
A curious outcome occurred during a recent study when mice who were engineered to have a particular immune deficiency were housed with healthy mice. The engineered mice developed fatty liver disease, and when they were placed in the same cage as healthy mice, the healthy mice began showing symptoms of liver disease and began to grow fatter.
The reason for this happening seems to be due to microbes in the stomachs of the mice. Unfavorable disease-associated bacteria increased dramatically in the mice with immune problems and was passed on to the healthy mice. These healthy mice also had changes occur in their stomach microbes and grew fat. In essence, one group of mice grew fatter because they were in the same cage as another group of already fat mice. Read: Trust Your Gut? Bacteria and Weight Gain
The question now being asked is if the same thing could happen between human beings although it is less probable. Mice eat the feces of one another, which is an effective way of transmitting stomach bacteria. Needless to say, people do not usually engage in this particular behavior and can experience yet another minute of gratitude for not having been born a mouse. Beyond that, the study does merit some attention. Read: Are Gut Bugs Keeping You Fat?
In good health,
Photo: Dr. Andrew Weil