Can Happy Rats Tell Us Something About Obesity?

All around us, we read mostly collegial (sometimes acrimonious) debates about how to do obesity and nutrition research right. Are randomized, controlled studies the best way to get definitive answers? What about nutritional epidemiology? Or animal studies? Some of these debates about methods and inferences are raucous. For a note of caution, we offer a story of happy rats and addiction.

The Rat Park

Bruce Alexander is a research psychologist who stirred up quite a controversy in addiction research with his Rat Park studies. Rats have long provided the classic metaphor for the power of addictive drugs. Rats in a cage with a choice between plain water and water with an opioid will go for the drug. They simply can’t resist it. Not even when it’s destroying them.

But Alexander wondered if the isolation of a cage might have something to do with these results. So he created an environment for happy rats. The Rat Park. There, these lab rats could mingle, play, and have sex. And in that environment, the rats had little interest in the opioid water.

Addiction scientists are still arguing about what this means. It’s hard to do naturalistic addiction research. Alexander’s research was so controversial that his university withdrew funding for it. All this happened back in the late 1970s and early 1980s.

But despite the controversy, the bottom line is clear enough. Context matters. Tightly controlled lab studies can tell us a lot. But they’re not the final word. Natural settings influence behavior and even physiology.

Lab Studies and Epidemiology

Quite a bit of angst is swirling right now about ultra-processed foods. Some animal and small human lab studies suggest food additives can have real metabolic effects. Moreover, a tightly controlled study of people in a metabolic ward found that ultra-processed foods might cause significant weight gain. Like caged rats, these subjects ate more of the ultra-processed foods. The size of the effect genuinely surprised the researchers who found it.

Is it the food? Or is it the effect of the food in a specific environment? Can we learn more from epidemiologists? Certainly, good epidemiology studies have found links between ultra-processed foods and health outcomes. Yet controlling for the social context remains a challenge.

We have much more to learn, and perhaps happy rats can teach us something. The systems that interact to influence food, lifestyle, and health outcomes are complex. Only with persistence, objectivity, and curiosity will we figure out how they really work.

Click here, here, and here for more about how the Rat Park studies have influenced thinking about studying addiction.

Cuddling Rats, illustration © Caroline / flickr

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October 20, 2019