You know that I hate Weight Watchers.

What you might not know is that for many people, going to the vet can take on rather the same flavour as a visit to your favourite weekly weight loss program. A visit to the vet, a diagnosis of canine/feline obesity and the next thing you know it’s a prescription for diet food, prescribed portions, a ban on treats, daily exercise orders, and weekly weigh ins. You can also go the medication route if lifestyle changes are ineffective. In 2007 the first drug to treat canine obesity was released.

And there are, of course, pet dieting competitions! See Pictures: Fat pets before and after slimming – BBC, photos from the annual UK pet slimmer of the year competition.

According to the Association for Pet Obesity Prevention, 53 percent of adult dogs and 55 percent of cats in the U.S. are obese or overweight. And it’s not just dogs and cats. twenty per cent of horses and bunnies are obese too.

There’s a lot of hand wringing about pets looking like their owners and about bad habits spreading and that our inactive, snack happy lifestyles are KILLING THE CUTE CATS AND DOGS! See Are you killing your pet with love? according to which doggie ill health and obesity is due to their fat, lazy owners.

Not sure if your cat is fat? Here’s a Fit or Fat? Infographic for cat owners.

(Now can you see why you might feel judged putting your pooch on the scale at the vets and finding out they’ve gained?)

This piece in the Atlantic What Are They Feeding You? 50% of U.S. Cats and Dogs Are Overweight gives you some of the flavour of the discussion if it’s new to you. It features photos of fat rabbits, before and after photos (of course!), and talks about exercise programs and personal trainers for Fifi and Fido. Sound familiar?

See also It’s Not Just Us: Even American Animals Are Getting Fatter  (The Wire).

Lack of companion animal activity and too much snacking mirrors the “move more/eat less” messaging that human animals hear. But what if it’s much more complicated than that?

It’s not just pets that are getting fatter. Lab animals are too. And that’s a puzzle.

Most intriguingly, perhaps, the laboratory animals showed more pronounced gains than those living outside a lab. This is strange because the sorts of lab animals the researchers looked at tend to be given lots of food and left to nibble at leisure. This practice has not changed for decades. That the animals put on weight nonetheless suggests the phenomenon cannot be caused solely by pet owners appeasing their Garfields, or feral rats rummaging through refuse composed of ever larger quantities of calorie-rich processed food. Dr Klimentidis is unable to pinpoint any single mechanism that could account for his results. But this does not stop his data from lending exculpatory explanations for fat tummies more credence.

Read the rest at The fat cat cometh: It is not just human beings that are getting fatter. Animals are, too (Economist).

Recently researchers have been looking at increases in animal size to help shed light on human weight gain. David Allison, a biostatistician at the University of Alabama at Birmingham was looking for a relationship between body weight and longevity in a population of marmosets but what he found made him wonder about the standard story about the causes of weight gain across all species.

The surge in human obesity is generally attributed to an increasing consumption of calories and a decrease in physical activity. “But maybe there are other things that are important — because those things can’t be acting on the marmosets, or the rats and mice in the National Toxicology Program,” he says.

See Lab animals and pets face obesity epidemic.

It’s also true for animals in zoos. See It’s Not Just All of the People Around You That Are Getting Fatter.

But while pets are on some level a reflection of the lives of their owners—they eat our food scraps and also, well, if you’re too lazy to go out and take your dog for a vigorous walk you’re not the only thing that’s going to get fat—zoo animals, whose lives are highly regimented and designed to promote health, are also growing around the middle. Chimpanzees get about the same food and the same level of exercise that they always have. And yet:

Among colonized chimpanzees, males and females, respectively, experienced a 33.2 and 37.2 per cent weight gain per decade, and a nearly 18-fold and 11-fold increase in the odds of obesity. In vervets, for females and males, respectively, there were 9.4 and 2.9 per cent increases in body weight per decade associated with 83 and 834 per cent increases in the odds of obesity. Among marmosets, females experienced a 9.7 per cent increase in body weight per decade, and a 1.73-fold increase in the odds of obesity. Among males, there was a 9.2 per cent increase in body weight per decade, and a 64 per cent increase in the odds of obesity.

Okay, so lab animals, pets, and zoo animals are often eating food that humans have produced. So maybe we could be to blame in these cases, even if we don’t exactly what we’re doing, we’re still doing something wrong. But what about wild animals? Some of them are getting bigger too.

For a discussion of possible causes–including electricity, viruses, and artificial lighting–read this fascinating essay by David Berreby, The obesity era: As the American people got fatter, so did marmosets, vervet monkeys and mice. The problem may be bigger than any of us.