Catching Obesity

Obesity overweightUPDATED: Is it possible that obesity, like the common cold is infectious? You’d think so if you believed research that’s been carried out over the last decade and hits the tabloid headlines again this week.

The research suggests that a highly infectious virus might be behind some cases of obesity. There is constant talk of an epidemic of overweight in the developed world. Overindulgence, lack of exercise, sedentary lifestyles are usually blamed. Occasionally, the words genetics or glands are mentioned, but rarely is the obesity epidemic thought of as a disease like, flu or winter vomiting virus, a disease you can “catch”, in other words. But, this research detracts from those genuine causes of overweight and might even do more harm than good, giving those with a less than healthy appetite another excuse to over indulge and avoid raising their heart rate above the average.

The research is highlighted today in several UK news papers and apparently lends weight to the idea that a highly infectious cold-like virus, known as AD-36 could cause obesity in some people.

It’s perhaps not surprising that, aside from the Daily Telegraph, most of the other outlets that report this work without real commentary are tabloids, the Daily Express, the Daily Mail, and Fox News, for instance. The original research is by Nikhil Dhurandhar of the Pennington Biomedical Research Centre in Louisiana and colleagues and will also be highlighted on the supposedly reputable BBC Horizon TV program this evening in an episode that attempts to answer the question, Why are thin people not fat?

Dhurandhar’s answer to that question is that those people simply haven’t yet caught the obesity bug. Apparently, the “virus goes to the lungs and spreads through the body. It goes to various organs and tissues such as the liver, kidney, brain and fat tissue…causes fat cells to replicate.” Moreover, the team’s latest paper published 22nd January 2009 in the journal Obesity, suggests that fat cells, known as 3T3-L1 cells, accumulate fat molecules (lipids) faster than normal when a person is infected with AD-36.

None of this is new, however. Dhurandhar and colleagues have been searching for an obesity “bug” for at least a decade. They published preliminary results in 1996 and 1997 and since then have apparently tested their theory in chickens, mice and marmosets. My good friend Tabitha Powledge wrote about the theory back in 2000 for Salon). Dhurandhar’s work on the viral theory of obesity also hit the news in the summer of 2007 when he reported details to the 234th national meeting of the American Chemical Society. At the time, the studies revealed that almost a third of people with obesity were infected with the AD-36 virus compared to just over one in ten of lean individuals. But does the presence of such a virus truly imply some obesity is due to catching an infection?

Last year, R.L. Atkinson of the Obetech Obesity Research Center, in Richmond, Virginia, reviewed the field and concluded that, “a portion of the worldwide epidemic of obesity since 1980 could be due to infections with human adenoviruses” (Int J Pediatr Obes. 2008;3 Suppl 1:37-43). More recently, Dutch researchers Vincent van Ginneken, Laura Sitnyakowsky, and Jonathan Jeffery, discussed Dhurandhar’s work in the journal Medical Hypotheses and agree with the findings: “We postulate that AD-36 may be a contributing factor to the worldwide rising problem of obesity,” they say, “We suggest the extension of comparative virological studies between North America and Europe, and studies between discordant twins (both dizygous and monozygous).”

The key phrases are “could be due” and “may be a contributing factor”.

It is very unlikely that, even for a proportion of individuals, will the viral theory prove to be the cause of their obesity. This is not the straightforward case we saw with peptic ulcers and the discovery of Helicobacter pylori. Even the link between gum disease bacteria and heart problems, while tentative, is more substantial.

It’s ironic that this research should come to the fore (again) within a week of the European Union giving the go ahead for pharmacists to sell the obesity drug Orlistat over the counter (OTC).

It is possible that for a small number of people the best defence against obesity would be to avoid catching this so-called obesity bug? Best way to avoid bugs? Enjoy a good diet, do not overindulge, and get plenty of fresh air and exercise and perhaps follow the how to avoid colds and flu tips too. Good nutrition, moderation and exercise will cover you for the biggest obesity risk factors, boost your immune system to a degree, and help you avoid adenoviruses infection. It’s a well-padded strategy, I’d say.

Research Blogging IconMiloni A. Rathod, Pamela M. Rogers, Sharada D. Vangipuram, Emily J. McAllister, Nikhil V. Dhurandhar (2009). Adipogenic Cascade Can Be Induced Without Adipogenic Media by a Human Adenovirus Obesity DOI: 10.1038/oby.2008.630

19 thoughts on “Catching Obesity”

  1. Obesity is the second leading cause of death. Numerous health problems are related to it. One should always involve doctor when making radical lifestyle changes, particularly when changing your diet or beginning an exercise program. It’s important to remember that our weight should be lost gradually. Don’t expect miracles overnight like some fad diets promise. Obesity can be control, visit here to know how

  2. Yes, you do seem to have strong opinions Kelsey, and they’re most welcome in the comments section on my blog.

    However, I wasn’t personally claiming that a virus is behind obesity, I was reporting on research results that suggest that might be the case in making some people more susceptible to accumulating fat tissue. Yes, “calories in-calories out” is obviously the overarching factor, but couple a virally induced susceptibility to fat accumulation with a leptin (appetite) hormone problem and you may have a recipe for serious weight issues. Oh, and what about those people who have both of those problems and are also debilitated physically in some way and so unable to exercise.

    It’s all very well for the fit and slim to criticize those with overweight problems, but it’s not necessarily a problem of sheer laziness or greed, and it certainly doesn’t address the problem.

  3. okay, and as another comment, i apologise for my informal language but i’m 15 and am researching new theories for science homework
    i have strong opinions & so wrote that.
    i understand that the main people reading & commenting this article are well justified on their opinions, probably being older.. more educated i suppose.

  4. rubbish
    you seriously think cos some lazy people become obese theres a virus behind it?
    nahh, some have medical reasons yes thats true
    but most peoples obesity is down to their own decisions and the way they live their lives.

  5. I’ve looked at the papers on this issue, and there is no doubt that AD36 is adipogenic in cell culture, and in certain animals can cause weight gain. What needs to be done is to identify the mechanism by which the virus induces the adipogenic program. If it’s real, then a mechanism will be identified and can be used to test the model in animals. If this work is fruitful, then we need a comprehensive epi study to determine association with infection. If cellular targets of AD36 are identified then these should be examined in people as well (eg for polys associated with disease).

    One nit-pick, David, please reserve the use of ‘antibiotics’ for bacteria. For viruses, use the term ‘antiviral’. As you know antiviral can be highly effective. Your sentence “Viral infections do not succumb to antibiotics anyway, (in fact bacteria often don’t either), so an antiviral diet pill is unlikely” is a bit confusing as a result (not to me, to the general public).

  6. Indeed, that’s exactly what the Horizon producers demonstrated with a group of young people. They tried to fatten them all up over the course of four weeks by doubling their calorie intake and precluding exercise. They were all fairly slim to start with and none of them got particularly fat, they all reverted to “type” within a couple of weeks of the “experiment” ending.

  7. The news on this claimed he was seeing 30% infection in overweight individuals tested, but on BBC Horizon he said 20%, so it’s not even as strong a correlation as the original hyperbole over the last 10 years has had it.

  8. Well, their model of 3T3-L1s is sort of cheating. These cells have been modified to be able to take up and hold lipid quite easily (meaning we only need to add two inducers to culture, along with insulin and lipids), all other cell lines need much more management . Are the cells in the body the same as the 3T3-L1s or the more finicky cell lines? Basically, until we understand the native cells, an in vivo model, this is not for sure, but we all need to start somewhere.

  9. In many species of animal one observes natural variations in size, activity level, and shape. For instance, I love catching a fat cutthroat, brook trout, or rainbow but they are rare in the wild.

    Domesticated livestock are bred for easy weight gain as are certain laboratory animals used in obesity research. Horses, on the other hand, look better and perform better if they are not obese. Consequently, horses are bred and fed differently from cattle; horses get very little grain.

    But humans – well we’re told to consume mostly grains and fruits and nuts and vegetables. But does it keep us slim or help us lose weight if we become fat? Not really. Force feeding experiments indicate that naturally slim people eating double their normal caloric intake will gain 12 to 15 pounds, remain at the new weight indefinitely, and gradually return to their starting weight when the normal feeding pattern is restored. In other experiments involving increased fat intake, subjects report feeling hot at times due to increased thermogenesis.

    This virus hypothesis likely contributes very little to our understanding of the current obesity epidemic because there are so many factors involving hormones, brown fat tissue, stomach size, intestinal surface area, and nutrient intake that affect appetite, fat utilization by muscle tissue, and fat storage in adipose tissue.

    There may indeed be increased incidence of AD-36 viral infections due to lowered fat intake and decreased sun exposure. Lauric acid and several other saturated fats and vitamin D3 provide some protection from viral infections of many sorts. Unfortunately, we’re told to avoid saturated fats as much as possible to prevent heart disease and avoid sun exposure to prevent skin cancer.

    My own experience with 25+ years on a high-saturated fat diet indicates that I can vary fat intake tremendously without affecting my weight. However, a little extra fruit, bread, or sugar causes weight gain even during periods of high physical output. But that’s just me.

    Regarding vitamin D3, I took 2’000 IU these past two summers and achieved substantial protection from sunburn. However, 2,000 IU does not seem to protect me from from colds and flu. Suffered a bout of each last winter. This winter I’m taking 4,000 IU. No symptoms thus far.

  10. Yeah but being fat doesn’t have to come by really overeating. You all know that one or two cookies over and above your intake a day, will result in weight gain. So in one year, you gain 10 pounds, the next another 10, so in 20 years you are 200 pounds heavier.

    I honestly suggest amphetamines (mommas little helper) alla the 50’s. I don’t really care what is good for me, we just want to look good, let’s be frank.

    I’ve used phentermine (picked up during vacations for years (not phen phen) and every year i can loose 20 pounds in one month, and just keep things careful. If I gain it back in a year or two…..back to phentermine, loose the weight again, and start all over.

    Guess what. ZERO health problems and I’ve done this over and over again.

    If you want to loose weight, you need a helper, not just some stupid doctor telling you to eat crappy salads and running miles a day. I can watch my weight, but only with the help of an appetite suppressant. They should be pushing suppressants more…that’s really all we need.

  11. I originally wrote this post first thing this morning and obviously wasn’t fully awake as it didn’t seem to say what I’d intended it to say in my haste to get the facetious remarks in about colds and flu, so it’s been redrafted slightly, specifically after re-reading following Milo’s comment.

  12. You know… my inner skeptic is starting to growl at this one. Sure, there may be a fatty virus… but will we as a society stop and admit that even if there is a fat bug, we still have to take responsibility for our own health?

  13. The team seems to be very successful at getting news coverage for their work over the last decade, but we are apparently no closer to a “proof”, so I too feel the jury is very much still out on this one. Moreover, their work does suggest it is only a factor in obesity for less than a third of sufferers. That could still be significant if we could screen for the virus in individual’s with risky socioeconomic and genetic profiles and ensure that they are immunised or given antivirals at an appropriate point. Or, we could heed Robert’s comment and simply carry on warning people that too many calories in and not enough exercise is the real root cause of the so-called obesity epidemic.

  14. I’ve bought into the idea that obesity, and other diseases, can be the result of some bug infecting us, but it’s still not like demonic possession. It’s more like a disability to be overcome. If I balloon out, I can’t just say “The devil made me do it.” I still have the free will and responsibility to just say no when the server asks “you want extra grease with that?”

  15. Judging by how unsuccessful I was in avoiding catching a cold during the past week (one that manifested itself in the most severe manner this weekend), I don’t like my chances in avoiding this “fat virus.”

    My jury is still out on this one, however. Much more study is needed before we can shift the blame of obesity onto a virus. There are many other contributing factors to obesity, including mental health issues that must be addressed as well. It doesn’t help when these things get front page coverage from tabloids and Fox News (or should that be “including Fox News”). This coverage provides pseudolegitimacy to a inadequately supported theory.

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