Breaking down the science and controversy behind this weight loss device
In the world of diet trends, we’ve seen some wild ideas: cabbage soup diets, cotton balls, tapeworm pills (seriously), and now…the DentalSlim. Sounds like a sci-fi toothbrush, right? But it’s actually a weight loss device. One that literally locks your mouth shut.
Developed by researchers at the University of Otago in New Zealand, the DentalSlim Diet Control is a metal contraption fitted to your back teeth, limiting how much you can open your mouth, about two millimeters. That’s just enough to sip liquid, talk (sort of), and breathe. In other words, when it’s engaged, you’re on a liquid diet whether you like it or not.
The device is being promoted as non-invasive, reversible, and cost-effective. According to the researchers, it’s not meant to be a long-term solution, but rather a temporary aid for people who need to lose weight quickly before undergoing surgery. Their small study showed that participants lost an average of 6.36 kg (about 14 lbs) in two weeks. After that, the magnets were released and normal eating resumed…for now. But let’s be honest: if it walks like a crash diet and talks like a crash diet (or doesn’t talk at all, because your jaw is locked), it’s a crash diet.
Even more concerning is how familiar this sounds. Jaw-wiring for weight loss was attempted back in the 1980s. It led to all kinds of issues. Jaw stiffness, difficulty speaking, choking hazards, gum disease, and psychological distress. DentalSlim may be the high-tech version, but it’s still serving the same idea: short-term results through restriction and discomfort.
In fact, in their own study, participants reported discomfort, difficulty speaking, and embarrassment, ultimately leading to their impression of life being less satisfying overall. Still, they stuck it out for two weeks. Probably because they had to. Let’s talk about the bigger picture.
For anyone preparing for surgery, weight loss might be recommended to reduce visceral fat or shrink the liver, both of which can improve surgical outcomes, particularly for laparoscopic procedures. But here’s the catch: for best recovery, you want to preserve muscle and improve nutrient status, not deplete your body with an ultra-restrictive liquid diet.
Liquid diets, especially those enforced by something like DentalSlim, typically result in water and muscle loss, not fat loss. And that’s a problem. Muscle is critical to healing post-surgery and maintaining a healthy metabolism long-term. Without it, recovery gets harder and sustainable results become less likely.
And don’t forget about fiber, or rather, the complete lack of it in a liquid diet. Fiber is essential for digestion and blood sugar regulation. Without it, the glycemic impact of your meals goes up, increasing the burden on your liver and potentially contributing to more inflammation, the opposite of what we want.
Let’s also be real about the mental and emotional side of things. People considering weight loss surgery are often in a fragile state. Adding a device that restricts eating, limits speech, and reduces quality of life? That’s not just unhelpful, it actually has the potential to be harmful. If someone is already feeling hopeless or isolated, this kind of intervention could do more psychological damage than good.
In my work with clients, a big part of the process is increasing satisfaction with life, not decreasing it. The goal is to create habits and strategies that feel empowering, not punishing. When your approach to health makes you feel worse emotionally or socially, it’s time to rethink the method. Yes, weight loss surgery can be incredibly helpful and even life-saving for some. But even then, success depends on what happens before and after. And no matter what approach someone chooses, nutrition is only one piece of the puzzle. We have to work on healing our relationship with food, our body, and ourselves for long-term success.
So, while I appreciate New Zealand’s commitment to innovation, this is one I recommend skipping. The ability to lock your jaw shut and sip your way to short-term weight loss might sound like a quick fix, but it doesn’t promote true health. It doesn’t support mental well-being. And it doesn’t build habits that last.
The bottom line is: just because a thing exists doesn’t mean it’s a good idea.