Mayo Clinic Proceedings article explores possible link between obesity and viral infections

October 23, 2007

ROCHESTER, Minn. -- Experts don't dispute the important role that diet and activity play in maintaining a healthy weight. But can poor eating habits and a less active lifestyle fully explain the prevalence of obesity in the United States today? That question has led some researchers to ask whether there might be other causes for this serious problem. In the October issue of Mayo Clinic Proceedings, researcher Richard Atkinson, M.D., asserts that there is a growing body of evidence demonstrating that viruses may play a role in causing obesity in humans.

"The cause of obesity is not a secret -- if you consume more calories than you burn in daily activity, you gain weight. What is interesting is that much of the obesity epidemic cannot be explained just by Americans eating more and exercising less. There are other factors at play, and viruses causing obesity may be one of them," say Dr. Atkinson.

Dr. Atkinson, director of Obetech Obesity Research Center in Richmond, Va., reviewed multiple published articles that demonstrate a connection between viral infections and obesity. His article in Mayo Clinic Proceedings discusses five animal viruses and three human viruses that have been shown to cause obesity in laboratory studies.

According to Dr. Atkinson, several studies offer ample evidence that animals infected with certain human viruses experience excess weight gain and fat storage. When researchers infected animal subjects with a human virus known as Human Ad-36, they reported measurable increases in the infected animals' body fat and the visceral fat that surrounds the organs deep within the belly. In addition, studies also demonstrated that infection with Ad-36 and the resulting weight gain could be transmitted from infected animals to uninfected animals.

Information on virus-induced obesity in human subjects is much more limited. Citing his own study conducted in 2005, Dr. Atkinson also showed a connection between obesity and exposure to the Ad-36 virus in humans. Dr. Atkinson's study screened for antibodies to Ad-36 (a sign of exposure to this virus) in 502 people of varying body weights, both obese and non-obese, from three cities in the United States. Ad-36 antibodies were found in 30 percent of obese individuals and 11 percent of lean individuals. Study results also showed highly significant differences in body mass index (BMI) between antibody-positive and antibody-negative individuals.

Dr. Atkinson also highlighted a study that looked at 89 sets of American adult twins and screened them for Ad-36. Because twins tend to be similar in many characteristics, including body weight, the researchers looked at twin pairs where one twin tested positively for Ad-36 and the other did not.

"Antibody-positive twins were slightly, but significantly, heavier and fatter than their antibody negative co-twins," says Dr. Atkinson. "The infected twins had a higher BMI and a greater percent of body fat than the uninfected co-twins."

In the mid-1970s, a virus called SMAM-1 was believed responsible for an increased death rate among commercially raised chickens in India. SMAM-1 is associated with decreased immune function and an increased accumulation of body fat in infected chickens. Dr. Atkinson reports that one study tested 52 obese humans for antibodies to SMAM-1. About 20 percent had SMAM-1 antibodies, indicating exposure to this virus. The study participants who had these antibodies were heavier and had a higher body mass index compared with the antibody-negative group.

Dr. Atkinson's article also explores what current research has to say about the possible mechanisms underlying virus-induced obesity. Some research suggests that viral infections have a direct effect on adipocytes, cells that manufacture and store fat, turning on the enzymes of fat accumulation and recruitment of new adipocytes.

What's the next step for this research? According to Dr. Atkinson, "the body of evidence linking adenoviruses to obesity in humans is now sufficient to think about the next step. Ideally, we could prevent infection and virus-induced obesity with a vaccine for the obesity viruses. Development of a human vaccine will take several years."
-end-
A peer-review journal, Mayo Clinic Proceedings publishes original articles, reviews and editorials dealing with clinical and laboratory medicine, clinical research, basic science research and clinical epidemiology. Mayo Clinic Proceedings is published monthly by Mayo Foundation for Medical Education and Research as part of its commitment to the medical education of physicians. The journal has been published for more than 80 years and has a circulation of 130,000 nationally and internationally. Articles are available online at www.mayoclinicproceedings.com.

To obtain the latest news releases from Mayo Clinic, go to www.mayoclinic.org/news. MayoClinic.com (www.mayoclinic.com) is available as a resource for your health stories

Mayo Clinic

Related Obesity Articles from Brightsurf:

11 years of data add to the evidence for using testosterone therapy to treat obesity, including as an alternative to obesity surgery
New research covering 11 years of data presented at this year's European and International Congress on Obesity (ECOICO 2020) show that, in obese men suffering from hypogonadism (low testosterone), treatment with testosterone injections lowers their weight and improves a wide range of other metabolic parameters.

Overlap between immunology of COVID-19 and obesity could explain the increased risk of death in people living with obesity, and also older patients
Data presented in a special COVID-19 session at the European and International Congress on Obesity (ECOICO 2020) suggests that there are overlaps between the immunological disturbances found in both COVID-19 disease and patients with obesity, which could explain the increased disease severity and mortality risk faced by obese patients, and also elderly patients, who are infected by the SARS-CoV-2 virus that causes COVID-19 disease.

New obesity guideline: Address root causes as foundation of obesity management
besity management should focus on outcomes that patients consider to be important, not weight loss alone, and include a holistic approach that addresses the root causes of obesity, according to a new clinical practice guideline published in CMAJ (Canadian Medical Association Journal) http://www.cmaj.ca/lookup/doi/10.1503/cmaj.191707.

Changing the debate around obesity
The UK's National Health Service (NHS) needs to do more to address the ingrained stigma and discrimination faced by people with obesity, says a leading health psychologist.

Study links longer exposure to obesity and earlier development of obesity to increased risk of type 2 diabetes
Cumulative exposure to obesity could be at least as important as actually being obese in terms of risk of developing type 2 diabetes (T2D), concludes new research published in Diabetologia (the journal of the European Association for the Study of Diabetes [EASD]).

How much do obesity and addictions overlap?
A large analysis of personality studies has found that people with obesity behave somewhat like people with addictions to alcohol or drugs.

Should obesity be recognized as a disease?
With obesity now affecting almost a third (29%) of the population in England, and expected to rise to 35% by 2030, should we now recognize it as a disease?

Is obesity associated with risk of pediatric MS?
A single-center study of 453 children in Germany with multiple sclerosis (MS) investigated the association of obesity with pediatric MS risk and with the response of first-line therapy in children with MS.

Women with obesity prior to conception are more likely to have children with obesity
A systematic review and meta-analysis identified significantly increased odds of child obesity when mothers have obesity before conception, according to a study published June 11, 2019 in the open-access journal PLOS Medicine by Nicola Heslehurst of Newcastle University in the UK, and colleagues.

Obesity medicine association announces major updates to its adult obesity algorithm
The Obesity Medicine Association (OMA) announced the immediate availability of the 2019 OMA Adult Obesity Algorithm, with new information for clinicians including the relationship between Obesity and Cardiovascular Disease, Diabetes Mellitus, Dyslipidemia, and Cancer; information on investigational Anti-Obesity Pharmacotherapy; treatments for Lipodystrophy; and Pharmacokinetics and Obesity.

Read More: Obesity News and Obesity Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.