Technology could trick the brain into thinking it’s time to stop eating
by Heather Allen
We are almost at the end of January, and by now many of our New Year’s Resolutions for 2024 have gone by the wayside. That gym card hides at the back of the wallet, the tracksuit gathers dust in the wardrobe, and the new trainers nestle undisturbed in their box. Meanwhile, telling ourselves it’s too cold to diet, we are too stressed, upset, or ‘the diet starts next week,’ we pile the sweet treats and fat-laden snacks onto our plates and into our mouths. We know that, if we seriously want to lose weight, we will have to put down the cake and pull on the trainers. Whatever diet and exercise combo we decide on, action needs to be taken, and we don’t expect it to be easy.
Indeed, as obesity rises through the western world, scientists have stepped up the search for ways to make weight loss easier. One possible solution has been developed by researchers at the Massachusetts Institute of Technology (MIT). Engineers at MIT have designed the VIBES pill, an ingestible capsule that vibrates inside the stomach and creates a sense of fullness. The technology relies on the signals sent by the stomach to the brain when a large meal has been eaten. Researchers say that swallowing the capsule before a meal could trick the brain into thinking it’s time to stop eating, offering a minimally invasive, cost-effective way to treat obesity.
Dr Shriya Srinivasan, a former MIT graduate student and now assistant professor of bioengineering at Harvard University, is the lead author of the new study. Dr Giovanni Traverso, an associate professor of mechanical engineering at MIT and a gastroenterologist at Brigham and Women’s Hospital, is the senior author of the paper. “For somebody who wants to lose weight or control their appetite, it could be taken before each meal,” Dr Srinivasan said. “This could be really interesting in that it would provide an option that could minimise the side effects that we see with the other pharmacological treatments out there.”
The pill’s mechanism works with the body’s response to satiety. When the stomach becomes distended, specialised cells called mechanoreceptors detect the stretching and send signals to the brain via the vagus nerve. When the signals are received, the brain stimulates production of insulin, as well as hormones such as C-peptide, Pyy, and GLP-1. All of these hormones work together to help people digest their food, feel full, and stop eating. At the same time, levels of ghrelin, a hunger-promoting hormone, go down.
While a graduate student at MIT, Dr Srinivasan became interested in the idea of controlling this process, using vibration to artificially stretch the mechanoreceptors that line the stomach. Previous research had shown that vibration applied to a muscle can induce a sense that the muscle has stretched farther than it actually has. For this study, Dr Srinivasan, Dr Traverso, and a team of researchers designed a capsule about the size of a multivitamin, that includes a vibrating element. The pill was designed to be orally ingested, to activate upon submersion in gastric fluid, to vibrate with sufficient amplitude to stimulate the gastric nerves, and to pass safely through the gastrointestinal tract. When the pill, powered by a small silver oxide battery, reaches the stomach, gastric fluids dissolve a gelatinous membrane that covers the capsule, completing the electronic circuit that activates the vibrating motor. After a set time period, the pill is safely excreted.
The VIBES pill was tested on a group of ten Yorkshire pigs, as a pig’s gastric anatomy is similar to humans. The pill’s effects were evaluated across a total of 108 meals. The researchers found that, as expected, once the pill begins vibrating, it activates mechanoreceptors in the stomach, which send signals to the brain through stimulation of the vagus nerve. The researchers tracked hormone levels during the periods when the device was vibrating and found that they mirrored the hormone release patterns seen following a meal, even when the animals had fasted.
The researchers then tested the effects of this stimulation on the animals’ appetite. They found that when the pill was activated for 20 minutes before the animals were offered food, they consumed 40 per cent less, on average, than when the pill was not activated. The animals also gained weight more slowly during periods when they were treated with the vibrating pill.
The VIBES pill is designed to vibrate for 30 minutes after being swallowed, but the researchers are hoping to develop a version which remains in the stomach for longer periods of time, where it could be turned on and off wirelessly. In the animal studies, the pills passed through the digestive tract within four or five days. The study also found that the animals did not show any signs of obstruction, perforation, or other negative impacts while the pill was in their digestive tract.
Dr Srinivasan believes that the capsules could offer an affordable solution to the obesity crisis, as they could be manufactured at a cost that would make them available to people who do not have access to more expensive treatment options. “At scale, our device could be manufactured at a pretty cost-effective price point,” she said. “I’d love to see how this would transform care and therapy for people in global health settings who may not have access to some of the more sophisticated or expensive options that are available today.”
The researchers now plan to explore ways to scale up the manufacturing of the capsules, which could enable clinical trials in humans. Such studies would be important to learn more about the devices’ safety, as well as determine the best time to swallow the capsule before a meal and how often it would need to be administered.
Other authors of the paper include Amro Alshareef, Alexandria Hwang, Ceara Byrne, Johannes Kuosmann, Keiko Ishida, Joshua Jenkins, Sabrina Liu, Wiam Abdalla Mohammed Madani, Alison Hayward, and Niora Fabian. The research was funded by the National Institutes of Health, Novo Nordisk, the Department of Mechanical Engineering at MIT, a Schmidt Science Fellowship, and the National Science Foundation in the US.
The paper, ‘A vibrating ingestible bioelectronic stimulator modulates gastric stretch receptors for illusory satiety’ can be accessed at https://www.science.org/doi/10.1126/sciadv.adj3003