This Is Your Brain on Walnuts
Eating walnuts activates the area of the brain that regulates hunger and cravings, according to a brain imaging study conducted at Beth Israel Deaconess Medical Center in Boston. Walnuts are high in nutrients and some research has suggested they promote feelings of fullness and may discourage overeating, but this small study is the first to demonstrate that walnuts have an effect on the brain.
The study involved 10 people with obesity who lived in a controlled environment – a research center -- for two five-day sessions. During one session, participants were given daily smoothies containing 48 grams of walnuts – the recommended serving size. In the other session, they received walnut-free, but nutritionally comparable, smoothies flavored to taste exactly the same.
Following each five-day session, the researchers used functional magnetic resonance imaging (fMRI) to observe brain activity while the participants were shown images of desirable foods (hamburgers, desserts), neutral items (flowers, rocks), and less desirable foods (vegetables). After consuming the walnut-rich diet for five days, the participants had increased activity in a part of the brain called the right insula when they were shown images of highly desirable foods.
According to researchers, this area of the brain is involved in cognitive control, which indicates the participants were paying more attention to food choices and selecting healthier options over highly desirable choices. Results of the study were published in Diabetes, Obesity and Metabolism.