Walnuts: control appetite by activating targeted brain regions
New and effective diets are reported every day. In general, nuts have long been recognized as one of the most valuable foods, they have a positive effect on our metabolism and are very suitable for the prevention of cardiovascular disease. Scientists have now been able to prove in a study that especially walnuts are ideal for being promoted during a diet to lose weight. Walnuts trigger a positive feeling of satiety, which is very beneficial for weight loss.
For the first time, researchers at Beth Israel Deaconess Medical Center (BIDMC) have been able to show the neurocognitive effects of walnut consumption in their current study. They found that consuming walnuts activates brain regions responsible for controlling hunger and cravings. The researchers published their findings in the journal "Diabetes, Obesity and Metabolism".
Brain activity in consuming walnuts is studied
To determine how walnuts work in the brain, scientists use functional magnetic resonance imaging (fMRI) imaging techniques. They are able to observe activity in the brain and determine which brain regions are activated when consuming walnuts. Ten obese volunteers were transferred to the clinic for two five-day study periods where they received a strictly controlled diet. So scientists don't have to depend on subject data for their food consumption, but can understand this.
The subject receives a walnut smoothie or a Placcebo drink
During the five-day session, subjects receive daily smoothies containing 48 grams of walnuts (recommended by the American Diabetes Association). During the second study period, they received a placebo smoothie that was free of walnuts, but comparable to nutrients flavored with walnut smoothies. The order of the two study periods was randomly selected so that some participants consumed walnuts first and others placebo. "Neither volunteers nor researchers know in the session where they received crazy smoothies," BIDMC explained in a press release about the results of the current study.
Less hungry after consuming walnuts
As in previous observational studies, subjects in this study reported that they were less hungry for a week when they received walnut smoothies. In the investigation using functional magnetic resonance tomography on the fifth day of the trial, clear reasons could be determined, according to scientists. The subject shows consumption after walnuts when looking at pictures with delicious, rather unhealthy and unpleasant foods, rather healthy foods significantly increase activity in the brain region, which is called insula.
The active area of the insula is likely to be involved in cognitive control of the decision to eat certain foods, the researchers said. As a result, the participants focused more on food choices and chose healthier and tastier options. The researchers emphasize that there is no ambiguity in the results of the study.
"When participants ate walnuts, a part of their brain shone, and we knew it was in line with what the subject reported: they were less hungry and more comfortable," said study leader Christos Mantzoros.
Effect of food on brain activity
"We don't often think about how what we eat influences activity in our brain," said study author Olivia M. Farr of the Department of Endocrinology, Diabetes and Metabolism at BIDMC. The current study shows clearly that there is also evidence in brain activity for lower welfare and hunger after consumption of walnuts. In other words, digestible food has direct neurocognitive consequences in the brain, which in turn has a significant impact on eating behavior.
In the next step, the researchers plan to test the number or dose of different walnuts to see if more nuts cause more brain activation or if after a certain amount the maximum effect is reached. In addition, neurocognitive effects from other foods must also be investigated. (FP)