CHOMP medical pros teach a nutrition class at the grocery store.

Grocery shopping has never struck me as a challenge, but going to Save Mart under the tutelage of a dietician changes things. Suddenly every aisle becomes a minefield.

I recently joined a group of a half-dozen participants for a tour of the cavernous Sand City grocery store, led by Tess Warwick, a registered dietitian at Community Hospital of the Monterey Peninsula, where we met in the seemingly innocuous wine aisle.

“I’m going to start with the bad news: Alcohol is basically empty calories,” Warwick told the group by way of introduction. “It gets stored as fat – literally, the beer belly.”

Someone asked the obvious questions: What about moderate drinking, and the supposed virtues of red wine?

Warwick wasn’t having it.

The secret of moderation, she said, is that serving sizes are different for everyone: Women are allowed one 5-ounce glass of red wine as a “moderate” serving, while men are allowed two.

“This is good,” one man said. “This was worth the trip!”

The trip, an hour and 15 minutes at a cost of $20 – not unlike investing grocery money into your shopping education – was eye-opening in some areas.

It was also fun because our group of increasingly conscientious shoppers bonded over eating habits. One participant, Helmut Schonwalder, who was raised in Germany and now lives in Monterey, had commentary of his own to offer when we got to the bread aisle.

“It’s made in a lab,” he told me as I examined a loaf of whole-wheat Dave’s Bread – the same stuff I’d eaten toasted for breakfast. “They’re financed by Pfizer. Sooner or later you have to take medication to digest this stuff.

“If it’s got more than 10 [ingredients], we don’t want it. Bread, with all the chemicals, the coloring, it’s like 40 or 50 items.”

Warwick’s critiques tend to be a little gentler, but she also didn’t shy away from slamming certain food groups, and even ranking brands.

“Welcome to the candy aisle,” she said as we turned down the cereal aisle. We passed the sweetened options entirely and headed for the cereals Warwick told the group were viable options: Shredded Wheat is the best breakfast cereal, she said, and Raisin Bran is a close second, despite 18 grams of sugar per serving – that’s from the raisins, real fruit.

While Warwick declined to give specific dietary counsel to any one member of the group, based on what might’ve been targeted health goals like lowering cholesterol or controlling diabetes, sugar was a culprit everywhere we looked, from bread to yogurt.

We spent a while in the peanut butter section, examining ingredient labels and abiding by Warwick’s advice to look for the second ingredient – in many cases, sugar.

She also delivered helpful peanut butter storage instructions: Don’t pour off the oil on top of the peanut butter jar. Instead, store it upside down to help it emulsify and keep it spreadable, as the fat is good fat. Her favorite peanut butter is Costco’s Kirkland brand.

In addition to peanut butter, she advocates for more beans – and less animal protein. (She also understands the convenience of canned beans, but recommends rinsing them first, a step that can remove as much as 70 percent of added sodium).

Just when it felt like we’d found reasons to embrace the conveniences of the modern grocery store, we entered the dreaded snack aisle, full of pretzels, chips and crackers.

“There are lots of tricks going on in this grocery store, where they’ll make multiple servings in one package,” Warwick warned.

She gets it – “I’m a realist, and I want some chips in my life,” she said – but that’s the tricky part.

“Some chips” according to many of the serving-size labels are five or six chips at a time. I’m even more dismayed to learn that Warwick treats coconut oil as an equivalent to butter or Crisco.

When we got to the milk aisle – not so much an aisle as an intimidating wall of milk, with well over a dozen choices – Warwick instructed the group to opt for 1-percent or skim. But by then, Schonwalder was ready for a debate. He argued in favor of whole milk, saying it keeps him and his wife full until lunchtime, so they avoid snacking through the morning.

“You want a certain amount of fat in the morning,” he said. He also volunteered his test for cheese: If you put it on the windowsill and it melts, it’s good; “the other stuff turns into plastic.”

There was good news when we ended in the produce section.

“This is your pharmacy aisle,” Warwick told the group. “It’s like a prescription.”

Schonwalder picked up a bunch of beets and his wife Tae Hui picked up a bunch of bananas, and finally everyone in the group started really shopping, smiling in a rare shame-free zone.

CHOMP’s next supermarket tour happens 6-7:15pm Thursday, Jan. 26, at Nob Hill, 1320 S. Main St., Salinas. $20/person, $25/couple. For a complete schedule, 649-7220, www.chomp.org/your-health/classes-events