Nuts, specifically eating walnuts, activates a region of the brain involved in the control of hunger and food cravings, which is why they make people feel full after eating just a few. What is going on here? Researchers at Beth Israel Deaconess Medical Center (BIDMC) have conducted a brain imaging study that reveals the neurocognitive impact of eating a walnut. The researchers knew people felt fuller after eating walnuts, but they wanted to see the evidence of activity changing in the brain. The team invited 10 obese individuals to live in the Clinical Research Center at BIDMC for two five-day sessions, during which they drank smoothies on a daily basis that contained either 48 grams of walnuts or no walnuts (the placebo). Both smoothies tasted exactly the same. Function magnetic resonance imaging (fMRI) allowed the researchers to see whether eating walnuts had had any effect on the neural control of appetite. The participants reported feeling less hungry during the walnut-consuming session than they did during the placebo-consuming session. To investigate further, participants were shown images of desirable foods such as hamburgers, neutral objects such as rocks and less desirable foods such as vegetables, and reactions were observed using fMRI scans. On viewing the highly desirable foods, there was increased activation in a brain area called the right insula after participants had eaten walnuts for five days. The right insula is thought to regulate hunger and food cravings, which would enable the participants to focus more easily on sensible food choices and select healthier or less desirable foods over the less healthy, highly desirable foods. The researchers plan to use the findings to help people to better maintain their weight and their health.