Interesting: Animals are getting fatter, too

[salvorhardin]

If it were just dogs and cats, I might suspect that pet owners accustomed to larger portion sizes were just super-sizing their doggy dinners too, but this is a much larger number of species which does indeed suggest something environmental.

All 24 populations of animals, which ranged from primates housed in research facilities to feral rats living in the greater Baltimore area, showed significant increases in body weight. Average body weights of captive chimpanzees increased at a rate of 33 percent each decade, and 9 percent per decade in captive marmosets. Laboratory mice got 12 percent fatter every ten years, laboratory rats did by 3 percent; the average body mass of Baltimore's feral rats increased by almost 7 percent each decade. And house pets were no exception, either. The average weight of cats increased by almost 10 percent each decade, while dogs' weights increased by 3 percent every decade.

Not only did body weight increase significantly, but so did the chances than an animal would be obese. In 23 out of the 24 populations, animals were more likely to be obese -- defined as weight above the 85th percentile at the initial time-point -- at the second time-point than at the first.

What's more, the increased body weights and increased likelihood of obesity were found even in animals whose diets and physical activity levels were known to be the same throughout the study period. So if dietary changes and energy imbalance weren't responsible for the rise in obesity, said Allison, it may be some environmental factor.

"If we're seeing these trends in other mammals, it shows that there must be another explanation" besides the main culprits of inertia and poor diet, Kuk said.

Full article: http://www.the-scientist.com/news/display/57821

[LaurenG]

1. What are we feeding them? It has to be something in the food supply

weird.

[salvorhardin]

2. Not necessarily

It could be a virus or other pathogen that's spread through the air. As Warpy has noted here many times before, the rise in obesity follows a classic epidemiological pattern. It could be a specific chemical in the food supply or drinking water too. Or it could all be a complex socioeconomic effect, or even all three.

[LaurenG]

3. That is really interesting. I hadn't heard that hypothesis before.

I vaguely remember hearing that histamines might have something to do with weight gain but I haven't read anything further to back that up either.

[salvorhardin]

4. A number of researchers have posited an "obesity virus"

The one you keep hearing about in the news the Human Adenovirus 36. But nobody has shown causation in humans yet. Here's a decent review article.

Viruses as an Etiology of Obesity
Richard L. Atkinson, MD

Obesity is a serious chronic disease that has numerous etiologies. The prevalence of obesity has increased dramatically since about 1980 in the United States and worldwide in both developed and developing countries. This rapid spread is compatible with an infectious origin. This review discusses the 5 animal viruses and 3 human viruses that have been shown to cause obesity and examines the evidence to date for virus-induced obesity. The obesogenic animal viruses include canine distemper virus, Rous-associated virus type 7, Borna disease virus, scrapie agent, and SMAM-1. The first 4 viruses attack the central nervous system to produce obesity. SMAM-1, an avian adenovirus from India, acts directly on adipocytes and is the only animal virus that is associated with human obesity. The 3 human adenoviruses, adenovirus (Ad) 36, Ad-37, and Ad-5, that are associated with obesity also affect adipocytes directly. These viruses stimulate enzymes and transcription factors that cause accumulation of triglycerides and differentiation of preadipocytes into mature adipocytes. Ad-5 and Ad-37 have been shown to cause obesity in animals. Ad-36 has been studied the most and is the only human adenovirus to date that has been linked with human obesity. Ad-36 causes obesity in chickens, mice, rats, and monkeys and was present in 30% of obese humans and 11% of nonobese humans. In twins discordant for infection with Ad-36, the infected twins were heavier and fatter than their cotwins. The growing body of evidence demonstrating that viruses produce human obesity supports the concept that at least some of the worldwide epidemic of obesity in the past 25 years is due to viral infections.
Full text: http://www.mayoclinicproceedings.com/content/82/10/1192.full

[LaurenG]

5. Thank you - this is fascinating. nt

[dixiegrrrrl]

7. Any readly available test for the viruses?

And how would one treat such a virus?

[salvorhardin]

9. Yes

In fact, the author of that review article I posted, Richard Atkinson, now runs a company called Obetech which performs various tests for the AD 36 virus. http://www.obesityvirus.com/services.html

However, there's no treatment yet, and it's still not clear that AD 36 causes obesity. So just knowing whether or not you have antibodies specific to the AD 36 virus isn't going to really help you. A bit of a waste of $200-$400 if you ask me.

[hedgehog]

11. When did GMO corn hit the food supply? Even cats and dogs are corn fed,

just read the ingredient list on any sack of pet food.

[salvorhardin]

12. Viral theories of obesity and the obesity epidemic predate GMO corn by about a dozen years n/t

[Tumbulu]

13. about 15 years ago....

and recently sugar beets became gmo and the cheaper veggies oils- canola and soy and cottonseed. I think that you are on to some part of it.

[Abq_Sarah]

14. Most likely the same crap

That we're (generally speaking) eating.

[tridim]

6. Maybe space-time is expanding faster than we assumed?

[LaurenG]

8. then everyone would be obese not just 1/3 of us. Duh!

:Djk

[hedgehog]

10. In an interaction between genetics and environment, including

exposure to viruses, not everyone will react the same way. For example, many diseases such as lupus and rheumatoid arthritis are felt to be due to an immune system primed by genetics and set off by an infection.