Walnuts Light Up Brain Region That Controls Appetite
By Heather Callaghan, Editor
Unique study reveals documented mechanism of just a few walnuts to decrease hunger signals
A recent two- or three-part, double-blind study demonstrated that less than half a cup walnuts (0.44 cup or 48 grams to be exact) per day made a significant difference in hunger levels on obese, post-menopausal women. But the study didn’t stop there…
First…from Science Daily:
The scientists recruited 10 volunteers with obesity to live in BIDMC’s Clinical Research Center (CRC) for two five-day sessions. The controlled environment of the CRC allowed the researchers to keep tabs on the volunteers’ exact nutritional intake, rather than depend on volunteers’ often unreliable food records — a drawback to many observational nutrition studies.
During one five-day session, volunteers consumed daily smoothies containing 48 grams of walnuts…
[…]During their other stay in the CRC, they received a walnut-free but nutritionally comparable placebo smoothie, flavored to taste exactly the same as the walnut-containing smoothie. The order of the two sessions was random, meaning some participants would consume the walnuts first and others would consume the placebo first. Neither the volunteers nor the researchers knew during which session they consumed the nutty smoothie.
As in previous observational studies, participants reported feeling less hungry during the week they consumed walnut-containing smoothies than during the week they were given the placebo smoothies.
The fMRI scans are what make this study truly unique… Although this was a small study on just a few women, the brain scans can tell no lies…
While in the machine, study participants were shown images of desirable foods like hamburgers and desserts, neutral objects like flowers and rocks, and less desirable foods like vegetables.
When participants were shown pictures of highly desirable foods, fMRI imaging revealed increased activity in a part of the brain called the right insula after participants had consumed the five-day walnut-rich diet compared to when they had not.
“This is a powerful measure,” said Dr. Christos Mantzoros. “We know there’s no ambiguity in terms of study results. When participants eat walnuts, this part of their brain lights up, and we know that’s connected with what they are telling us about feeling less hungry or more full.”
They think the insula might be involved in cognitive control and salience. Weirdly, they think the region lighting up means that participants were selecting the “less desirable” or healthier options over the more visibly appealing or “junky” foods. Could walnuts help or reset a taste for healthier foods? Only time will tell…
Walnuts are a brain food that have fats that are ideal for a woman’s reproductive system. They contain omega-3 fats like Alpha-lipoic Acid, for instance, that our bodies can potentially convert to DHA and EPA fats.
Some people are sensitive to fats and may wish to limit their consumption to 1-2 ounces of nuts like walnuts. Some people start eating them and cannot stop! But if walnuts can play a role in controlling the factors of obesity like appetite control, than a dietary solution to a dietary problem is an ideal one to consider.
Beth Israel Deaconess Medical Center. “In a nutshell: Walnuts activate brain region involved in appetite control: First-of-its-kind study reveals mechanism of walnuts’ documented ability to decrease hunger.” ScienceDaily. www.sciencedaily.com/releases/2017/08/170816181259.htm (accessed August 17, 2017).