I've heard of people who've convinced dentists to wire their mouths shut as a method to control eating. The DentalSlim Diet Control has the same result but is perhaps a bit more subtle. According to the University of Otago researchers who developed it, the gadget consists of a set of "custom-manufactured locking bolts" that attach to the wearer's back teeth and "allows the wearer to open their mouths only about 2mm, restricting them to a liquid diet, but it allows free speech and doesn't restrict breathing." From the University of Otago:
Participants in a Dunedin-based trial lost an average of 6.36kg in two weeks and were motivated to continue with their weight loss journey.
Lead researcher, University of Otago Health Sciences Pro-Vice-Chancellor Professor Paul Brunton says the device will be an effective, safe, and affordable tool for people battling obesity. It is fitted by a dentist, can be released by the user in the case of an emergency and can be repeatedly fitted and removed[…]
The practice of surgically wiring people's jaws shut became popular in the 1980s, but it came with risks; vomiting brought with it the risk of choking and after 9 to 12 months the patients developed gum disease. In some cases, there were continuing issues with restriction of jaw movement and some developed acute psychiatric conditions.
"Alternative strategies are required which may obviate surgery, or which reduce weight prior to surgery and so make it easier and safer.
"The beauty of it is that once patients are fitted with the device, after two or three weeks they can have the magnets disengaged. They could then have a period with a less restricted diet and then go back into treatment," he says.
Here's their scientific paper published in the British Dental Journal: "An intraoral device for weight loss: initial clinical findings"