A remarkable new implantable device developed by engineers at University of Wisconsin–Madison promises a new way to battle obesity. By gently stimulating a nerve that links the stomach to the brain, the device tricks your brain into thinking you're full.

The most common current surgical procedure to treat severe obesity involves bariatric procedures such as gastric bypass. These procedures are generally quite effective but they are also dangerously invasive and come with a swathe of challenging side effects. A newer strategy that has arisen over the past few years is called vagus nerve stimulation (VNS).

The vagus nerve is a large conduit that communicates signals between the brain and the body. It has been discovered that this communication pathway is one of the ways the stomach signals to the brain that it is full and our appetite should be suppressed so we stop eating. Experiments have shown that artificially stimulating the vagus nerve can reduce feelings of hunger, essentially making the brain think the stomach is full.

In 2015 the FDA approved the first obesity-controlling device of its kind, a pacemaker-like system that disrupts these vagal nerve communications to help suppress a person's appetite. This device, called "Maestro" was somewhat effective, but it's also incredibly bulky, difficult to operate, and needs to be frequently connected to external batteries to be recharged.

The newly developed VNS device offers a truly impressive leap forward over the "Maestro." It is tiny, battery-free and generates its electrical stimulations in response to real-time stomach movements. The device is powered by the undulations of the walls of the stomach, meaning it not only needs no battery but it only activates its stimulation in response to the peristalsis of the stomach when a person begins eating.

"The pulses correlate with the stomach's motions, enhancing a natural response to help control food intake," says Xudong Wang, one of the authors on the study. "It's automatically responsive to our body function, producing stimulation when needed. Our body knows best."

The device has not been tested in humans at this point, however, the researchers recently completed animal testing and the results were incredibly promising. In a rat model the device resulted in a rapid 35 percent weight loss in the first 18 days of activity. For the remaining 75 days of the experiment the animals sustained that average weight loss, and once the devices were removed they immediately returned to normal eating patterns and weight levels.

The next steps for the researchers involve further refining the implantable device, perhaps to add some kind of shutter switch that allows the system to be easily turned on or off. Larger animal tests will also be conducted before moving into human trials, but the team is optimistic this system will present a huge leap forward in obesity-prevention technology.

"Our expectation is that the device will be more effective and convenient to use than other technologies," adds Wang.

The new research was published in the journal Nature Communications.

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