We recently hosted an article by scientist and guest blogger Stephan Guyenet that explained how certain foods—those with a high calorie density, fat, starch, sugar, salt, free glutamate (umami), certain textures (easily chewed, soft or crunchy, solid fat), certain flavors, an absence of bitterness, food variety, and drugs such as alcohol and caffeine—could trip reward systems in the human brain. Those reward systems, then, encourage people to eat more of the foods that trigger the reward. The result, says Guyenet, is a cycle that could be the link between the American obesity epidemic and the rise of highly processed convenience foods, designed specifically to trip those neural reward systems.
This theory, and several related theories, are increasingly popular in the scientific community. This week, there's an opinion piece in the journal Nature Reviews Neuroscience that looks at the strengths and weaknesses of these theories and talks about what research needs to be done going forward. It's kind of a space for researchers to step back and say, "Okay, here's what we know, here's what's not lining up with what we think we know, and here's what we have to do if we want to understand this better." In the context of science, an article like this isn't really a slam against the ideas it analyzes. Instead, it's meant to summarize the state of the science and share ideas that could either strengthen the case, or lead down entirely new roads.
Sadly, you can't read this article unless you have a subscription to Nature Reviews Neuroscience (or pay them $32 for single article access).
Luckily, Scicurious, a neuroscientist and an excellent blogger, has read the article, and has a nice run-down of what it's saying and what you should know. Some of the ideas being discussed here overlap with Stephan Guyenet's research. Some don't. But this is connected enough that I thought you guys would be interested in reading more and getting more perspectives on this issue. Let me make this clear, though: Guyenet isn't doing bad science. As with a lot of scientific research, there's often more than one way to look at the same data. Scientists can disagree without one person having to be all-wrong and another all-right. In fact, having different scientists working on the same subject is a key part of getting the facts right.
As you read, you'll notice that an important place where Scicurious' perspective really differs from Guyenet's is in terms of connecting the idea of "addiction" to certain foods back to the idea of an obesity epidemic.
...is there a place for food addiction? The authors think so, and I am inclined to agree. However, it needs to be much more stringent than the current model of food addiction that many people want to embrace (the idea that sugar makes you addicted or that being overweight means you have a problem). Changes need to be made.
First off, it's important to separate food addiction from obesity. Binge eating does not necessarily mean you are overweight, and being overweight does not necessarily mean that you binge eat. Ranking by BMI is not going to work.