"Slow down! Don't eat so fast!"

Like generations before me, I grew up hearing those words. Yet, despite the best of parental intentions, I continued to scarf down my chicken nuggets at a record pace. Until last week, that is, when the nagging reappeared in the form of a "smart" fork.

The $100 HAPIfork vibrates in your mouth when you eat too fast and wirelessly reports your good (or bad) habits to your smartphone. No, this isn't a "Saturday Night Live" parody of a late-night infomercial product. Its maker, Hapilabs, claims the fork will help you eat slower, which in turn will help you curb overeating and lose weight.

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And while the fork has it faults, using it for two weeks has challenged me to think more about what I take from my plate.

Two bites within 10 seconds and the fork will reprimand you with a buzz of the tines and a blinking red light. The vibration is quick and painless—think electric toothbrush. Separate your bites by 10 seconds or more and the fork stays quiet and blinks green to show approval. You can decrease or increase the interval between bites, but Hapilabs says 10 seconds is ideal when the goal is to make a well-proportioned meal last 20 minutes, something dietitians I spoke to recommend.

The HAPIfork weighs 2 ounces and contains an accelerometer to sense movement and a rechargeable battery. Hapifork

At over 2 ounces, the HAPIfork doesn't feel like fine flatware. It's heavier and longer than typical utensils because inside the dishwasher-safe fork is a tech component with an accelerometer, battery and other guts. As weird as it is to charge a fork, at least you can use a standard Micro-USB phone-charging cable. The battery lasts close to five days.

During setup, the fork asked me to identify my eating style. Was I a "picker" or a "scooper"? The fork is supposed to use this to recognize movements, but I still had to move the fork to my mouth in very specific way for it to recognize each bite. When I used the tines to stab chicken and broccoli, it registered all my bites, but almost none of my scoops of rice were counted.

While eating I kept one eye on the app's countdown on my phone. "Great timing!" it blinked when I separated bites by more than 10 seconds. It's fun to watch as it instantly sends data via Bluetooth to your phone, but "I'm tracking my bites!" surely isn't an acceptable excuse for keeping a phone out at mealtime. The iPhone and Android apps tended to be sluggish and unresponsive at times.

The company says it is working to fix the app bugs and other fork issues.

The app lets users know when they've raised a forkful of food too soon. Joanna Stern/The Wall Street Journal

While I've yearned to "accidentally" leave the HAPIfork behind at restaurants, the gadget has successfully slowed my eating. I've more carefully chosen each bite knowing the next one is a long 10 seconds away. I've even eaten less at some meals. But if I eat slowly, will I really shed pounds?

There is scientific evidence that links fast eating to overeating, but experts told me it takes more than eating slowly to achieve weight loss.

"It's what you put on that fork that makes a difference," said Roberta Larson Duyff, a registered dietitian. Waiting longer between bites "might mean less food, but you still have to fill that fork with healthier options."

And as Tufts University nutrition professor Susan Roberts painfully reminded me, many of the most fattening foods—chips, ice cream, hamburgers, french fries—aren't eaten with a fork. "Most Americans probably only eat a third to a half of their calories with a fork," she said.

"I wouldn't eat that if I were you," I'm envisioning a next-generation HAPIfork saying, in a Siri-like voice, as I dig into fried chicken. But for now, the fork isn't advanced enough to know what you're eating. You need to use the app to track manually what you put on the fork.

The author's recent fork servings as tracked by the app. Hapifork

The most useful part of the HAPIfork experience has been creating a record of my food intake. I'm more aware of good and bad choices and can better plan my menus for the day. But the app's food-tracking capabilities aren't quite up to par compared with other software. It only lets you upload photos of your meal and include a description of what you ate. A good app should allow you to count calories, log specific items and see an overview of your day.

That's why I prefer MyFitnessPal or Livestrong's MyPlate. Available for iOS and Android, both apps have great meal databases with caloric information. MyFitnessPal has a slightly larger database than MyPlate, with rarer entries like "Stumptown coffee" or "Caveman cookies," but MyPlate has a better designed app and website. Best of all, both apps are free.

So there's no need to fork over $100 for a utensil to solve the biggest weight-loss challenge: choosing the veggies over the nuggets.

—Contact Joanna at Joanna.Stern@wsj.com and on Twitter @joannastern.