How to break up with sugar this Valentine's Day

"Sweets for my sweet, sugar for my honey ... "

We've been using sugar to express our love and affection since long before the Drifters first crooned that tune. While Shakespeare was actually referring to flowers when he wrote the 17th-century line in "Hamlet" that inspired the song, heart-shaped boxes of chocolates have been around for more than 150 years.

The connection between love and sweets is enduring — in no small part because of our own biology. Still, there are signs that this link is weakening, or at least being challenged, by health-conscious folks, doctors, school principals and even prolific Pinterest pinners.

I have a bit of an ulterior motive in exploring these questions because today, on Valentine's Day, we are officially halfway through the Star Tribune's 28-Day Sugar-Free Challenge. Along with more than 2,600 readers, community members and many of my colleagues, I am attempting to avoid all added sugars until March. Even on this candy-driven holiday.

But I'm learning that breaking up with sugar isn't so easy. In fact, it goes against taste preferences that evolved millions of years ago. Humans developed a sweet tooth, evolutionary biologists say, because we came to associate a sweet taste with high-energy foods that helped us survive through lean times.

Sweet foods like ripe fruits provided better fuel for ancient humans who had to forage for food, especially compared with plants that were much less energy-dense. Our ancestors also connected a bitter taste with plants that might have harmful toxins, likely prompting them to seek out food that tasted sweet while avoiding bitter stuff. And of course, we spend the first months of life drinking sweet mother's milk.

As we evolved, humans also domesticated plants and fruits, cultivating them through breeding and grafting to make them even sweeter and to have less seeds and fiber than they did in the wild. As Michael Pollan explains in "The Botany of Desire," even apples — the fruit that now packs so much sweetness in grafted varieties like this year's Minnesota State Fair favorite, the First Kiss — are bitter in the wild.

For much of human history, sweet fruits were seasonal delights and refined sugar was a luxury — first refined in India, then the Arab world and eventually driving slavery in the Western Hemisphere's plantations. Sugar was something that regular people didn't get to taste much, writes Gary Taubes in his book about sugar's unhealthful side, "The Case Against Sugar." That changed with the Industrial Revolution in the 1800s, when sugar prices dropped and sources of the sweet stuff expanded.

The origins of Valentine's Day itself are still being debated by historians, but most everyone agrees that the sugar-filled trappings of the day as we know it arrived in 1861.

That's when British chocolate manufacturer Richard Cadbury created a heart-shaped box to sell his "eating chocolates," one of the first products to use solid cocoa butter to create candy instead of selling chocolate as a drink.

True to the Victorian sensibilities of the time, he covered the pretty boxes with Cupids and flowers. Even once all the chocolates had been gobbled up, the empty boxes became popular places to stash love letters, according to cultural historian Amy Henderson. And the idea of giving sweets to a sweetie really took hold.

Candy-makers in America soon picked up on the commercialization of Valentine's Day, and Milton Hershey began mass-producing chocolate Kisses in 1907. They still are in demand, judging from the recent social media outcry over a manufacturing mishap that caused the tips to be broken. (The problem has since been remedied, but Kisses with tips won't be on the shelves until well after Valentine's Day this year.)

Clara Stover started making candies in her Colorado kitchen in 1923, an operation that expanded into Russell Stover, which is still the top-selling boxed-chocolate maker in the country. Now, it is owned by the Swiss company Lindt & Sprüngli, and its latest offerings include "sugar free" versions made with the natural substitute stevia, angling for those of us trying to have our chocolates and eat them, too, so to speak.

Researchers today are looking into the ways that sweetness interacts with the reward center in our brain — just like seeing a photo of someone we love romantically, eating sugar causes dopamine to spike — and are exploring whether sweet foods really do give kids a "sugar rush."

This phenomenon has overwhelming anecdotal evidence, but study after study has found that sweets don't actually make kids hyper — parents just think sugar makes kids hyper. Even so, there are plenty of health reasons to avoid giving kids too much sugar — and parents, teachers and principals have been working to make schools soda- and candy-free zones.

The once traditional Valentine's Day candy fest at school, complete with those ubiquitous paper-covered shoe box mailboxes, is slowly becoming a thing of the past.

When Stacy Whitman first started an online pledge five years ago, calling on parents across the country to refrain from sending candy for their kids to hand out at school on Valentine's Day, she couldn't get many to sign on, she said. They told her they associated the holiday with candy and didn't want to be told what to do.

She was undeterred. "I think parents who are trying to 'break up from sugar' can have an impact by leading by example," said Whitman, who runs a food nonprofit in Idaho.

Now, to avoid classroom distractions and allay concerns over health and food allergies, a growing number of elementary schools don't allow candy to be shared or attached to valentine cards. Some, like those in the Edina school district, don't celebrate the holiday in class at all. What to do instead?

Pinterest users have responded by collecting scores of cute and clever ways to attach a trinket like a pencil ("You're the write friend for me"), glow stick ("You light up my life") or even mini Play-Doh tubs ("You're a-doh-able") to a printed valentine. The seasonal aisles at places like Walgreens have expanded accordingly, offering much more than candy. This year, they are dominated by special Valentine's editions of Squishmallows, the latest hot stuffed animal. The oddly appealing creatures' maker, Jonathan Kelly of Kellytoy Inc., called Valentine's the "biggest plush purchasing and giving event of the year."

Plenty of Americans are still buying candy, though. Overall, spending on Valentine's Day candy has risen slightly over the past decade, according to the annual National Retail Federation survey, even as the number of Americans who say they plan to celebrate the holiday has declined by more than 10 percentage points over the same time frame. Starting in 2015, candy actually surpassed greeting cards as the most popular gift, the survey found.

Still, as far as sugar overconsumption goes, candy is a small part of the problem. It accounts for only about 6 percent of the total sugar in the American diet, writes Samira Kawash in her 2013 book "Candy: A Century of Panic and Pleasure." Processed food and sugary drinks are the real culprits.

"While candy shares much with its processed-food kin, candy is the one kind of processed food that proclaims its allegiance to the artificial, the processed, the unhealthy," Kawash writes.

"This is something I really like about candy: It's honest. It says what it is. But this honesty also makes candy an easy target. By blaming candy for bad nutrition, cavities and obesity, we can keep buying without worry the foods that stock the rest of the grocery store aisles."