This Is Why They're Fat: What Cheesecake-Addicted Rats Reveal About Human Obesity

According to a new study, lab rats fed on high-fat food (like cheesecake) exhibit brain changes that resemble addiction. So is a fatty diet addictive in humans? And is such addiction responsible for obesity?

Researchers at The Scripps Research Institute in Jupiter, Florida found that rats given unlimited access to high-calorie foods — sausage, bacon, cheesecake — showed neurological changes in their reward levels. That is, they needed to keep eating the high-fat food in order to “feel good.” They also ate only the high-fat food even if lower-fat rat chow was available, and if the high-fat food was taken away, they refused to eat chow for an average of 14 days. Since human addicts sometimes have a lack of dopamine receptors, researchers deactivated these in some rats — and found the rats showed even faster changes in reward levels. Most rats offered the high-fat food ate about twice their normal number of calories, and became obese.

Though Katherine Harmon’s recap of the study in Scientific American does distinguish between drug addiction and overeating (“The sticky part about studying food addiction is that, unlike cocaine or alcohol, humans can’t exactly drop it-cold turkey or not”), it’s sure to be cited alongside studies on sugar to prove that our modern diet is as addictive as crack. SciAm‘s headline makes this explicit: “Addicted to Fat: Overeating May Alter the Brain as Much as Hard Drugs.” On the one hand, this research does give interesting insight into why people often have a hard time changing their eating habits — if humans are like rats (obviously, a big if), then perhaps eating a lot of sausage actually rewires our brains.

However, Harmon notes that obesity is more complicated than simple cheesecake addiction. Some people naturally have fewer dopamine receptors than others, which may predispose them to both drug abuse and overeating even before they take their first bite of bacon. As Harmon reported just a few days ago, genes can also influence gut microbes in mice, upping their chances of obesity and diabetes. And of course, humans are subject to all sorts of other genetic and environmental influences, from medications that cause us to gain weight to metabolic syndromes that can make us obese even if we don’t overeat. So while it’s interesting that a high-fat diet can change how rats’ brains work, it’s important to note that not all weight gain is the result of binging on cheesecake.

Addicted To Fat: Overeating May Alter The Brain As Much As Hard Drugs [Scientific American]