The University of Minnesota scientist showed her subjects scenes from Hollywood tear-jerkers. A wave of melancholy swept over them as only happens when watching "Sophie's Choice."

Then she fed them gooey chocolate chip cookies as a salve for their emotional distress. The experiment led to a surprising discovery: The freshly baked cookies didn't soothe their pain.

Traci Mann, co-author of the 2014 study "The Myth of Comfort Food," is a real spoiler. She believes that "comfort food" is not all that comforting. Oh, and diets don't work, either.

"It seems like I'm always saying what people don't want to hear," said Mann, 46, who speaks in even tones that reflect her methodical nature.

A psychologist and author of the forthcoming "Secrets From the Eating Lab," she is best-known for her unconventional experiments that test — and often debunk — sacred beliefs about our eating behaviors.

Her meticulous, scientific approach to examining the seemingly obvious effects of eating habits on wellness has made her a rising star in the niche field of food psychology.

In her book, out April 7, Mann takes aim at the $20 billion diet industry. Diets don't help, she argues, because losing weight through sheer willpower is an improbable feat.

"People yell at me about this, but the data are so strongly on my side it's crazy," she said. "When I say diets don't work, I say they don't do what people want them to do." That is, lose weight and keep it off.

It struck her: Anything that's going to help people control their eating is going to work only if it doesn't require willpower. "You can't be strong enough to resist, so you have to be smart," she said. "You have to be clever about how you're going to deal with this."

Lab on a stick

Eating right is easier when you have a plan.

For instance, if you place a bowl of M&Ms across the room, Mann says, you will eat less candy than if the bowl is directly in front of you. What's really surprising, she said, is studies show that you will eat just as few M&Ms if you move the bowl a mere 2 feet from you. Putting a little distance between you and temptation can make a big difference.

"Us human folk — we are lazy," Mann said. "That's the bottom line. So an obstacle like that will slow us down."

What's worse: We're constantly bombarded by temptation — from TV ads to office snacks to the candy strategically placed near the cash register. As she explains in her book, our brains are wired for survival and not resistance. Dieting works against our nature. That's when willpower goes out the window.

Mann developed many of her healthy eating tricks from quirky experiments conducted in a campus laboratory called the Health and Eating Lab (HEL), or "hell," as her students like to call it. This was the scene of that groundbreaking comfort food study — co-authored with U researchers Zata Vickers and Joseph Redden.

The lab is outfitted with a bright red couch, a coffee table, a refrigerator and a small toaster oven. Mann keeps a stash of Hershey bars in an overhead cabinet for a current study.

On a recent afternoon, Mann and her students huddled together in the lab to dream up their next big experiment, to be conducted at the year's momentous eating festival — the Minnesota State Fair.

The fair is a gold mine for this type of research. It allows Mann to observe people in their natural habitat — in this case, at a place where the primary goal is gorging on the deep-fried food. This summer, she wants to stage what she calls a "sharing intervention."

The experiment would involve stationing observers by garbage cans and asking fairgoers whether they shared the cheese curds (or Pronto Pup or turkey leg) they just ate. Mann's students brainstormed ways they could encourage people to share their food, including handing out napkins with the message "share at the fair" printed on them.

"All this is good!" Mann told the students, pumping her fists. "I kind of have always wanted to try to prime sharing to see what happens."

Strategic eating

In the battle for better eating, it's the little tweaks that can really improve our health, Mann says.

At home in Edina, she uses a few strategies to keep herself and her family healthy. She dishes up food on small plates to control portion size. She and her husband use the word "treats" instead of "dessert" to try to limit the amount of sugar their two sons eat.

"Dessert implies it's the last course of the meal and it's there every time," said Stephen Engel, Mann's husband. By calling them treats, "then it's a little bit of a special occasion."

Mann does yoga, runs and works out with a personal trainer. But she's not obsessive or draconian about food, and even splurges once in a while. Her comfort food of choice: Peeps. In her kitchen hangs a vintage picture of a chocolate-covered Twinkie.

Her husband, also a U psychologist, said living with a person who studies eating behaviors isn't as intimidating as it might sound. Dining with Mann is "totally normal," Engel said, noting that she doesn't experiment on the family. Well, maybe a little bit.

"We may serve as her 'wild,' " Engel said, chuckling. "Sort of like a naturalist going out into the wild to watch people eat. Then she takes those observations and turns them into lab experiments."

Mann didn't set out to make a career out of being a spoiler.

Her knack for asking the question no one else has considered is a hallmark of her work, her colleagues say.

"She speaks the truth and she finds the truth," said A. Janet Tomiyama, a former student of Mann's who now teaches psychology at the University of California, Los Angeles. "When you can approach science nondefensively and with curiosity, you can reach some interesting findings."

Psychologist Andrew Ward has teamed up with Mann on several studies over the years.

"She's incredibly skilled and she's a very rigorous thinker," said Ward, who teaches at Swarthmore College and has known Mann since they were graduate students at Stanford University.

Back then, she raised questions about the effectiveness of a university program designed to combat eating disorders. The program had students listen to a panel of young women who had recovered from eating disorders.

Ever the skeptic, Mann conducted a study and discovered that the program, in fact, had the opposite effect on its audience. It was making things worse. "People who had seen it were more likely to have symptoms later," Mann said.

Did you eat your veggies?

One of Mann's most heralded findings tackled a seemingly impossible problem: getting kids to eat their vegetables. She employed a technique that works for her own children — serving vegetables first, before the rest of the meal.

"For most of us, when you have a vegetable on a plate with all the other food, the vegetable loses," she said. "You eat the other things and the vegetables are what gets left."

In the study, funded by the U.S. Department of Agriculture and co-authored with Redden, Mann tested the "veggies first" idea on students in Richfield public schools. At lunchtime, they found little cups of baby carrots on each table in the cafeteria.

While waiting for the rest of their lunch, they nibbled on the carrots. The result: Half the kids ate the carrots. Typically, only 10 percent of kids will eat carrots if they're served with other food, Mann said.

"They ate it because it was there and there was no competition," Mann explained. "So you've got to get rid of the competition."

Back at home on a recent Sunday, she and her husband prepared a dinner of grilled salmon with green beans and almonds. They invited the neighbors over and placed carrot sticks and hummus out for the kids. Again, Mann's theory worked. The kids munched on the carrots while the parents finished cooking the rest of the meal.

Later, as everyone gathered around the table to eat, Mann nudged her elder son, Ben, 13, toward a healthy choice. "Did you try the green beans?" she said. "They're really good."

He paused, considering her suggestion. Then, he piled a bunch on his plate.

After the meal, he and the other kids indulged in a treat — a couple of pieces of homemade fudge. Mann didn't object.

"We should get to enjoy things," she said. "We just need to find a way to enjoy a reasonable amount."

Allie Shah • 612-673-4488