This study looked at animals – over 20,000 animals, 8 species, living with humans or not. It found that, over the last few decades, the animals were getting fatter. The authors say the odds of this happening by chance are 1 in 10 million.

Canaries In The Coal Mine: A Cross-Species Analysis Of The Plurality Of Obesity Epidemics, Proceedings: Biological Sciences, June 2011

A dramatic rise in obesity has occurred among humans within the last several decades. Little is known about whether similar increases in obesity have occurred in animals inhabiting human-influenced environments. We examined samples collectively consisting of over 20 000 animals from 24 populations (12 divided separately into males and females) of animals representing eight species living with or around humans in industrialized societies. In all populations, the estimated coefficient for the trend of body weight over time was positive (i.e. increasing).

The probability of all trends being in the same direction by chance is 1.2 × 10−7.

Surprisingly, we find that over the past several decades, average mid-life body weights have risen among primates and rodents living in research colonies, as well as among feral rodents and domestic dogs and cats. The consistency of these findings among animals living in varying environments, suggests the intriguing possibility that the aetiology of increasing body weight may involve several as-of-yet unidentified and/or poorly understood factors (e.g. viral pathogens, epigenetic factors).

Even when they didn’t eat too much, even when they didn’t exercise too little. Just like us. They got fat:

Our findings reveal that large and sustained population increases in body weights can occur in mammalian populations, just as they have occurred among human populations, even in the absence of those factors that are typically conceived of as the primary determinants of the human obesity epidemic via their influence on diet (e.g. access to vending machines) and physical activity (e.g. less physical education classes in schools).

Even when they were fed as part of lab experiments; even when they were let out to pasture; even when, in the case of humans, they weren’t old enough to feed themselves:

• “Obesity … is a growing problem for dogs and cats … (and 2007) saw a 19% increase in claims related to obesity.”
• “Others reported that 19% of horses in a large cohort were obese, even among largely pasture-fed animals.”
• “An increase in body weights was observed among rats used in carcinogenicity studies in France between 1979 and 1991, despite similar husbandry conditions.”
• “It is also noteworthy that the obesity epidemic has also occurred among children of six months of age and under, an age group for which explanations involving food marketing, less physical education is schools, and more labour-saving devices seem questionable.”

You know what I think it is? Of course you do because I’ve been saying it for years. It’s chemicals in the environment, notably endocrine disruptors which are known to be obesogenic. These authors think so too:

One set of putative contributors to the human obesity epidemic is the collection of endocrine-disrupting chemicals (endocrine-disruptors), widely present in the environment.

And it’s not going to change anytime soon because makers of these chemicals, like Monsanto and their endocrine-disrupting product Roundup, are having a heyday with the lax regulation  of the current administration. Expect to hear more of the individual-blaming slogans, “Eat less, exercise more!”

Here’s a graph I picked up from the NIH a few years ago. Not that this means anything, but the use of the herbicide Roundup (a potent endocrine disruptor)  took off for agricultural uses in the late 70s. Genetically engineered crops were introduced in the mid-to-late 1990s. GMOs, designed to withstand heavy application of Roundup, were doused with the stuff.

Pesticides aren’t the only sources for endocrine disruptors. BPA in can linings and other plastics and plasticizers are also culprits. Our bodies carry in their tissues a lot more of these chemicals than the bodies of our parents and their parents.