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Effect in the brain How walnuts help to lose weight
The consumption of walnuts is associated with numerous health benefits, particularly in terms of metabolism and the cardiovascular system. In a recent study, US scientists have now shown that walnuts can also help with weight loss by giving them an increased sense of satiety.
For the first time, the researchers at the Beth Israel Deaconess Medical Center (BIDMC) have been able to demonstrate the neurocognitive effects of walnut consumption in their current study. They found that consuming walnuts activates a region of the brain responsible for controlling hunger and cravings. The researchers published their findings in the journal "Diabetes, Obesity and Metabolism".
Walnuts also develop a brain effect that increases satiety and control over cravings. (Image: karepa / fotolia.com) Brain activity in walnut consumption studied
To determine how walnuts work in the brain, scientists used the imaging technique of functional magnetic resonance imaging (fMRI). They were able to observe the 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 the scientists did not have to rely on the subjects' data on their food consumption, but could exactly understand this.
Subjects received walnut smoothie or Placcebo drink
During a five-day session, subjects received daily smoothies containing 48 grams of walnuts (recommended by the American Diabetes Association). During a second study period, they received a walnut-free, but nutritionally comparable, placebo smoothie flavored with the walnut smoothie. The order of the two study periods was chosen randomly, so that some participants first consumed the walnuts and others the placebo. "Neither the volunteers nor the researchers knew in which session they received the nutty smoothie," explains the BIDMC in a press release on the current study results.
Less hunger after walnut consumption
As in previous observational studies, subjects in the current study reported that they were less hungry during the week when they received the walnut smoothies. In the investigation by means of functional magnetic resonance tomography on the fifth day of the experiment, a clear reason could be determined, according to the scientists. The subjects showed after walnut consumption when viewing images with tasty, rather unhealthy foods and less tasty, rather healthy foods significantly increased activity in the brain region, which is referred to as insula.
Activation of the insula
The activated area of the insula is likely to be involved in the cognitive control of the decision to eat certain foods, researchers say. As a result, attendees focused more attention on food choices and opted for healthier, less palatable options. The researchers emphasize that there is no ambiguity in the study results. "When participants eat walnuts, that part of their brains shine, and we know that's in line with what the subjects report: they are less hungry and more comfortable," reports study leader Christos Mantzoros.
Influence of food on brain activity
"We do not often think about how what we eat influences our brain activity," says study author Olivia M. Farr of the Department of Endocrinology, Diabetes and Metabolism at the BIDMC. The current study shows clearly that there is also evidence in the brain activity for the well-being and the lower hunger after walnut consumption. In other words, ingested foods have direct neurocognitive consequences in the brain, which in turn have a significant impact on eating behavior.
In a next step, the researchers plan to test different amounts or dosages of walnuts to see if more nuts lead to more brain activation or if after a certain amount a maximum effect is achieved. In addition, the neurocognitive effect of other foods should also be investigated. (Fp)