There’s a piece of artwork in the cozy New York City restaurant The Smile that reads: “If you’re happy and you know it, keep it to yourself.”But should you? According to science, the answer is no. Smiling makes you more beautiful.When we’re young, we smile at practically everything (from your dad making silly faces to slap-stick cartoons to a new toy). Then somewhere between adolescence and adulthood, some of us start to grin less often. But here’s a reason to beam: Research shows that finding that genuine smile again may be a better beauty makeover than revamping your wardrobe revamp or splurging on an expensive haircut.

COLUMN: The Power of Smiles

In studies, subjects judge smiling faces as more attractive—the “reward regions” of the brain even light up in response to a grin. People also think you’re more sincere and competent with a smile on. That may be thanks to the “Halo Effect,” where having one good quality makes people assume you have a host of other beautiful qualities.

And that may be true. “People who smile are often friendlier, have a better sense of humor and are more socially engaging,” says YouBeauty Psychology Advisor Art Markman, Ph.D. What’s more, research also shows that women with a “duchenne smile” (a genuine smile where the eyes crinkle up) in their high school yearbook picture had better marriages and overall wellbeing 30 years later.So if we smiled more often would we appear more attractive? And would people think our personalities were as glowing as our grins?

Experiment: Smiling More Vs. Less

We did some very unscientific research to see how smiling plays out in everyday life. The question: If I were to smile more than usual, would people smile back and approach me? Would I get treated differently when I wasn’t grinning?Here’s what I found: On the day that I smiled less than usual, nothing out of the ordinary happened. It was a gloomy Monday and I wasn’t feeling too well so it was easier to not grin. Although it was hard to suppress a smile when a coworker said something funny, I basically stayed in my corner of the office and didn’t socialize much (so I suppose not grinning did have an effect after all).

QUIZ: What’s Your Humor Style?

Next, I prepared for a day of near-constant smiling. Before going ahead with it, I asked Dr. Markman if it’s creepy to smile all of the time. His answer? Kind of—yes. That’s because a frozen facial expression isn’t really communicative.

“All interactions are a dance,” he says. “If you’re dancing with someone who’s waltzing and you’re doing the Cha-Cha, you’re going to step on them and it’s not going to be a pleasant experience. The whole point of a good dance is people responding to each other. Conversation is the same way.”Also, smiling all day is forced—and a fake grin doesn’t garner the same beauty benefits. A 2011 study of bus drivers found that fake smiling (aka “surface acting”) actually depressed mood compared to “deep acting,” which is smiling by way of conjuring positive thoughts and memories. When they did the latter, not only did their moods improve, but their productivity also increased. With that in mind, I thought, how am I going to make my extra-smiley day genuine?

MORE: When Body Language Backfires

 I wanted to try out the all-smiles experiment on a day when I was over-the-moon ecstatic, but I ended up testing it out a week after my smile-free day. By the time I reached the office that morning, I had that fatigued facial muscle feeling you get after smiling for one too many photos.At first I was a little self-conscious grinning like crazy. For one, I didn’t want to send any flirting signals. But luckily I went through the whole day without anyone thinking I was hitting on them.

There were at least four smiles I received in return, which I don’t think I would have normally gotten while walking the streets of New York City. I would have liked to say this was the day I randomly got a free Starbucks offered to me or that someone said “they liked my style” or “I had good energy,” but I didn’t get any of those types of comments. I did, however, feel more energetic. In terms of having great social interactions, the days when I smile genuinely (versus constantly) are more fruitful.

MORE: Charm School: How to Be Magnetic

Do White Teeth Make a Difference in Your Smile?

I also tested out another theory—that white teeth make for an even more attractive smile. That may be because pearly whites are linked to youth and vibrancy. On the flip side, yellowy, dark teeth are a sign of aging because the enamel thins out as we get older, showing the darker dentin underneath. Our teeth also become porous, so they pick up stains more easily.

The quest for healthier-looking teeth goes back for centuries. As far back as 3000 B.C., people used “chew sticks” (aka, twigs) to clean their teeth. And—though gross—the ancient Romans discovered that ammonia from urine could whiten teeth. Fast-forward to today and you’ll see countless whitening gels, strips and toothpastes lining the isles. (These can remove stains so your teeth appear whiter, but they can’t actually whiten the tooth.) Aside from a diet of beets and coffee, other factors discolor our chompers: genetics, disease, poor hygiene and tobacco to name a few. The only procedures said to truly whiten teeth are done by a professional at the dentist’s office, such as the popular 45-minute Zoom whitening procedure, which uses UV rays to penetrate the stains on teeth. (Many celebs and TV personalities with blinding smiles have had professional whitening like this done so don’t think they just hit the genetic jackpot or use an amazing toothpaste.)

If we’re going to this much trouble to get a toothpaste commercial-worthy smile, does that mean it can actually boost your magnetism?“I don’t think it’s the smile,” says Dr. Markman. “It’s how it affects the smiler. It’s a self-fulfilling prophecy—you go out of your way to smile, which engages people more. If you feel you have a particularly winning smile, you’ll smile more. You interact more.”

MORE: What’s Your Smile Type?

I was going to repeat my experiment after getting my teeth whitened to see if people were that much warmer towards me. When I told my friends the plan, they said my teeth were already white enough. I started thinking about what really makes a genuine smile and decided to stick with my whitening toothpaste and not spring for professional whitening to go the extra mile (or eight shades). I also feared I’d be one of the few to actually end up getting side effects from the UV lights, even though it’s approved to be safe.Instead of perfectly pearly white teeth, I found something else that brightens up my smile: a berry velvet lip pencil that I glide right on when I need a pick me up.

I get at least one compliment a day when I wear it, which naturally makes me smile a little more.In the end, I learned that true beauty doesn’t come down to plastering on a rigid grin when you’re not feeling it or sporting the brightest shade of white teeth. Instead, it’s about feeling comfortable enough with your real smile to show it.

QUIZ: How Happy Do You Feel?