Is Obesity Contagious? You Won’t Believe What Research Is Showing!

If obesity is a disease, is it contagious?

Yes, it might be contagious as in “infectious disease.”

We already know that the behaviors that combine to cause obesity are contagious in the way that groups of people who spend a lot of time with each other tend to think and act alike too.

Obesity is classified as a disease by the A.M.A., but the debate hasn’t been laid to rest.

The argument that obesity isn’t a disease, is based on an argument that there are no specific symptoms associated with obesity.  Some maintain it’s not a disease, but rather, it is more a risk factor for other conditions.

“The suggestion that obesity is not a disease but rather a consequence of a chosen lifestyle exemplified by overeating and/or inactivity is equivalent to suggesting that lung cancer is not a disease because it was brought about by individual choice to smoke cigarettes,” some say.

Diseases can be contracted by lifestyle choices.

Hepatitis is a disease that gets spread when addicts use dirty needles. That makes it a disease contracted as a consequence of a dangerous lifestyle.

So let’s not belabor whether or not how one gets fat is what makes obesity a disease. That debate rages on, but it seems to be overlooked that obesity in some people may not be a result of a lifestyle choice, but caused by either bacteria or a viral infection!

Emerging research is recognizing a pathogen (disease-causing organisms, such as viruses and bacteria) may be one other influence on obesity as well as the already widely accepted causes: genetics, environment, and lifestyle.

The term Infectobesity was created in 2001 by Dr. Nikhil V. Dhurandhar, at the Pennington Biomedical Research Center as a result of studies showing that the origin of obesity in some people might be caused by pathogens.


The study of the effect of infectious agents on metabolism is still in its early stages. Gut flora has been shown to differ between lean and obese humans. There is an indication that gut flora in obese and lean individuals can affect the metabolic potential. This apparent alteration of the metabolic potential is believed to confer a greater capacity to harvest energy contributing to obesity. Whether these differences are the direct cause or the result of obesity has yet to be determined unequivocally.[1

An association between viruses and obesity has been found in humans as well as a number of different animal species. The amount that these associations may have contributed to the rising rate of obesity is yet to be determined.[2]


The fat virus is the popular name for the concept that some obesity in humans and other animals has a viral source. The AD-36 adenovirus has been observed to increase the amount of body fat on laboratory animals, an effect that has been duplicated on chickens and monkeys.

Ad-36 is known to cause obesity in chickens, mice, rats, and monkeys and was present in 30% of obese humans and 11% of nonobese humans. The prevalence of Adv36 positivity in lean individuals increased from ∼7% in 1992-1998 to 15-20% in 2002-2009, which paralleled the increase in obesity prevalence.

How you get a disease isn’t the way to determine what should or should not be a disease, but it it were, it looks like obesity qualifies for the classification!

Whether obesity promoting gut bacteria can be passed from person-to-person is unknown. However, it is known that an overgrowth of “bad” bacteria in the gut, termed dysbiosis, may be caused by a diet low in fibre, excessive alcohol consumption, antibiotic use or even chronic stress. Strategies that can increase “good” bacteria in the gut while decreasing levels of bad bacteria include increasing dietary fibre intake and the use of probiotic supplements.

There is some evidence from human studies to suggest that increasing dietary fibre intake and perhaps even using a probiotic supplement may help maintain a healthy body weight by improving the health of your gut bacteria. Avoiding high fat and sugar foods and consuming more unrefined foods from plants such as nuts, seeds, vegetables and fruits while minimising stress and using antibiotics sparingly may improve the health of your gut flora.

The more we know about obesity and its many causes, the better we can help people achieve and maintain healthy body weight. That’s potentially good news.

Maybe one day there will be a vaccination we can get to protect us from Infectobesity. Photo Credit:

Maybe one day there will be a vaccination we can get to protect us from Infectobesity.
Photo Credit:

There’s potentially bad news too.

I am concerned, however, that the hostile environment many obese people are already experiencing from fat-phobics may get even worse if skinny people start to worry that they’ll “catch obesity” from close interaction with fat people.



Jackie Conn

About Jackie Conn

Jackie Conn is married and has four grown daughters and four grandchildren. She is a Weight Watchers success story. She's a weight loss expert with 25 years of experience guiding women and men to their weight-related goals. Her articles on weight management have been published in health, family and women's magazines. She has been a regular guest on Channel 5 WABI news, FOX network morning program Good Day Maine and 207 on WCSH.