No nut is going to control me, you may say. You are your own person. You eat what you want, when you want. But science may say otherwise about walnuts.
What is up with deez nuts? Five researchers from the Beth Israel Deaconess Medical Center in Boston (Olivia M. Farr Ph.D., Dario Tuccinardi M.D., Jagriti Upadhyay M.D., Sabrina M. Oussaada, and Christos S. Mantzoros M.D., D.Sc., Ph.D.) conducted a study published in Diabetes, Obesity, and Metabolism. The researchers first randomly assigned ten hospitalized patients with obesity five straight days of either a smoothie with 48 grams of walnuts or a similarly tasting and textured smoothie without walnuts. Then after one month of returning to their original diets, those who first got the walnut smoothie then got five days of the non-walnut smoothie and vice versa. One participant eventually dropped out of the study, leaving nine who completed the whole protocol.
At the beginning of the study, the researchers measured each of the study subjects’ brain activity using a functional magnetic resonance imaging (fMRI) machine. After the 5 day smoothie diet, study subjects then underwent another fMRI to see how things had changed.
Then there was the food porn. The researchers showed the study subjects different pictures while undergoing the fMRI. Pictures included those of “highly desirable foods” (high-calorie or high-fat images, e.g., cakes, onion rings), “less desirable foods” (low-calorie or low-fat images, e.g.,, vegetables and fruits) and “non-foods” (e.g., flowers, rocks, trees). Yes, you rock and flower eaters may say that everything’s subjective, but these were the designations by the researchers. Before and after each fMRI scan, study subjects completed visual analog scales (VAS) to measure how hungry or full they felt.
The study resulted in two major findings. First, after the walnut smoothie diet, study subjects reported feeling less hungry than after the non-walnut smoothie diet. Secondly, following the five days of walnut smoothies, study subjects had differences in their brain activity (as measured by fMRI) when shown food porn. Specifically, the right insula part of the brain seemed to be more active. Parts of the insula may be responsible for satiety and inhibition. In other words, something about walnuts may be telling your brain to simmer down when shown mouth-watering food. This could be some Vulcan mind meld-like stuff: walnuts may help you control your appetite and thus help with managing your weight.
Of course, this is a very small study with measurements taken only over a short period of time. It also does not prove that walnuts can actually control your appetite or if any of the findings will persist over time. Effects can wear off as the brain and body get used to eating a certain type of food. More, larger, and more complex studies are needed before drawing stronger conclusions. But these results are encouraging. Note that the California Walnut Commission (CWC) did provide funding for this study. However, they were not directly involved in designing, conducting, interpreting, or reporting the results for the study.
These findings are not completely surprising. There is increasing evidence that food and their ingredients don’t simply just provide calories and nutrients to your body like emptying a dump truck into a hole (with the hole being your mouth). Food and ingredients may interact and communicate with your body in many different and mysterious ways. For example, the work of Tim Moran, Ph.D., Director of Behavioral and Biological Research for our Global Obesity Prevention Center (GOPC) and Paul R. McHugh Professor of Motivated Behaviors at the Johns Hopkins School of Medicine, has shown how your gastrointestinal tract and brain are communicating back and forth with each other to help regulate your hunger, cravings, and metabolism. Even though your body may seem relatively quiet (although some people’s bodies may seem louder than others), there’s a lot of discussion and maybe even arguments going on inside you. Here’s a talk from Dr. Moran for the National Academies of Science, Engineering, and Medicine that begins to show just how complex these systems are:
How noisy your body and brain may be may vary compared to others, depending on you and all of the cues around you. For instance, a recent study published in the journal Neuroimage and led by Susan Carnell, PhD, another member of our GOPC and Assistant Professor of Psychiatry and Behavioral Sciences, found that adolescents who are at higher obesity risk may have different brain activity patterns when presented with words representing different types of foods.
As Dr. Carnell explained, “When it comes to hunger and satiation, a calorie is not necessarily a calorie. Food with a high glycemic index, like pasta, are processed more quickly than those with a low glycemic index, like beans and nuts, so you may still feel hungry after consuming a large amount of mac and cheese.”
Thus, adding an ingredient here and there to your food, especially artificial ones, could change what your food is saying to you. For example, Alice Walton previously wrote for Forbes about how artificial sweeteners may even lead to weight gain by interfering with brain connections that usually associate the sensation of sweetness and energy intake. In other words, your brain may usually equate a certain amount of sweet food with a certain amount of calories. When this association is messed up (which is a scientific term), your brain may say something is screwed up, eat more food. That’s why the global obesity epidemic may be due in part to the content of our food having changed. Since the 1980’s more and more “manufactured” and highly processed food has entered our diets.
All of this reemphasizes how you, your surroundings, food, nutrition, health, and obesity really form very complex systems and how obesity is very complex problem. It also says that even when you are eating alone, you are not really alone. Your food is having conversations with your body and brain. You might as well say in your best Robert De Niro voice to your food, “you talkin’ to me?” The answer with walnuts is probably yes and maybe in a good way.