You can train your clients as hard as you want at the gym, but if they don’t buy the right foods at the supermarket, their fitness gains are sure to come up short.

Grocery shopping is a daunting task these days. Shoppers confront thousands of choices in stores brimming with questionable marketing claims and unsound nutritional options.

That’s why many clients are sure to benefit from a guided grocery store tour to help them bring home a bounty of healthful foods. A 2012 study published in the Journal of Nutrition Education and Behavior found that people who received a short nutrition counseling session before grocery shopping bought more healthy items, like fruits and vegetables, than those who received no shopping guidance (Milliron, Woolf & Appelhans 2012). So it appears that a shopping game plan can help your clients make more nutritious choices at the supermarket. To start, try implementing the following research-proven rules for a healthy grocery experience.

Rule #1: Come Prepared

Healthy grocery shopping starts before people leave the house—with a detailed grocery list that they don’t deviate from once they reach the store. A study in the Journal of Consumer Research found that people who chose their food from memory (that is, based on an immediate stimulus rather than a plan) were more likely to buy less-healthy food than were those who shopped from a grocery list (Rottenstreich, Sood & Brenner 2007). “A side effect of the task of putting together a grocery list ahead of time is that it promotes meal planning, which often leads to a healthier diet overall,” says Bonnie Taub-Dix, RD, author of Read It Before You Eat It (Plume 2010) and a nutrition expert in New York City. She adds that your list should reflect the layout of your favorite store, so you’re not back-tracking and being exposed to more poor food choices.

Also, if your belly is growling, you shouldn’t be shopping. A 2013 Cornell University study found that hungry shoppers bought almost 19% more food at a simulated grocery store, including 31% more high-calorie items, than those who ate a snack beforehand (Shackford 2013). “Grocery shopping when hungry makes tempting food look even more alluring, which can set the stage for unhealthy impulse buys,” advises Taub-Dix.

Also, it pays to avoid long lines. University of Arizona researchers found that people who had long waits at the checkout counter were up to 25% more likely to succumb to tempting snacks like the candy bars displayed there (Houser, Reiley & Urbancic 2007). Cut down on wait times by using the self-checkout or shopping during off-peak hours.

Rule #2: Choose Your Companions Wisely

Encourage clients to take their children shopping, Taub-Dix says. “The supermarket can be a classroom for healthy eating, full of teachable moments.” She suggests turning the outing into a game that transforms a grocery list into a scavenger hunt for healthy items. Depending on the children’s ages, parents will want to show them how to compare similar items, such as the sugar levels in boxed cereal. It’s also vital that children not have the ultimate vote in supermarket decisions. Another good idea is to go shopping with friends who have a similar desire to eat better.

Rule #3: Grab a Cart

Clients are better off grabbing a cart instead of a basket at the front door. A recent study in the Journal of Marketing Research found that pushing a shopping cart instead of lugging a basket made shoppers nearly seven times less likely to purchase chips and candies and other nutritionally corrupt foods (Tuttle 2011). The researchers surmise that the strain of flexing an arm while carrying a basket may encourage shoppers to gravitate toward vice foods, while extending an arm when pushing a cart may have the opposite effect.

Clients should fill the big part of their grocery carts with wholesome, nutrient-dense edibles like vegetables, fruits, low-fat dairy, lean meats and whole grains, and reserve the small section at the top for one or two naughty treats.

Rule #4: Linger in the Produce Section

Shoppers need to make a beeline for the produce section, then stay there. “You want to hit the fruit-and-vegetable aisles first, when you still have plenty of energy and are less likely to feel rushed to get out of the store,” recommends Taub-Dix. This encourages buying a bigger bounty of fruits and veggies that may help you dodge a number of killer diseases. A massive 2013 American Journal of Clinical Nutrition study involving more than 71,000 people aged 13 years and over determined that consuming five or more servings of fruits and vegetables each day can significantly increase survival period. People who ate three servings of vegetables daily lived on average 32 months longer than those who consumed fewer than three (Bellavia et al. 2013).

While strolling the produce section, get colorful to acquire a bigger dose of disease-fighting compounds. A study at Colorado State University found that people who ate several different phytonutrients from a wide variety of fruits and vegetables experienced lower levels of DNA oxidation—a sign of free-radical damage that promotes aging and disease—than those who ate larger amounts of only a handful of plant foods and, therefore, fewer total antioxidants (Thompson et al. 2006). To get a bigger variety of nutrients and antioxidants, include every color of the spectrum&emdash;green, red, yellow, orange, purple, white&emdash;in that shopping cart.

Rule #5: Live on the Edge

Be sure to guide people around the outskirts of the store before diving into the cramped middle aisles, where long-lasting nutritional danger lurks. “Besides fruits and vegetables, the perimeter of the supermarket is going to be where most of the healthiest perishable foods are kept, such as seafood, lean meats, eggs, whole-grain breads and dairy products,” observes Janis Jibrin, MS, RD, author of The Supermarket Diet (Hearst 2007) and lead nutritionist for

Jibrin suggests visiting the central aisles only for such necessary staples as oils, whole-grain cereals and healthy canned items like no-salt-added beans. Keep in mind, however, that many grocery stores are now also littering the perimeter with desserts and other high-calorie prepared fare.

Rule #6: Get Some Air

Supermarkets’ narrower inner aisles are designed to help you spot all those tempting—and nutritionally lackluster—packaged foods. Dawdling here can encourage shoppers to load up on excess calories, sugar, sodium and unhealthy fats, so educate your clients about the perils of those claustrophobic center aisles.

However, Jibrin notes that some cramped aisles, particularly in health food-focused stores, can offer convenient jarred, bagged and canned nutritional bright spots. These can include beans, canned fish, nut butters, whole grains, plain oats, no-salt-added tomato sauce and extra virgin olive oil. “A good rule of thumb when buying prepared foods from the inner aisles is to look for those with the shortest ingredient lists containing recognizable ingredients,” Jibrin adds. Fewer ingredients often translate into less fluff like refined sugar and sketchy additives.

Rule #7: Read Up

Label-reading should be a big part of a supermarket tour. Researchers in the journal Agricultural Economics looked at the shopping habits of 25,000 people and discovered that women who read food labels while grocery shopping weighed an average of 9 pounds less than those who didn’t (Science Daily 2012). Also, women were more likely than men to examine the nutrition and ingredient data on foods.

Grocery shoppers should be skeptical about jargon like “all natural,” “gluten free” or “cholesterol free” plastered on the front of packages. Instead, your clients should be reading the finer points of the Nutrition Facts label. It’s best to steer clear of foods with lofty calorie, sodium and saturated fat numbers. Look for products with higher numbers for fiber, unsaturated fats and protein. And don’t overlook the ingredient list, which provides vital intel on added sugars, whole grains and lab-derived preservatives.

If clients are on the hunt for lower-calorie products, clue them in on serving sizes and servings per container, which Taub-Dix notes is one of the most overlooked items on a nutrition label. “Don’t just assume the serving size listed on a granola or energy bar is a realistic amount a person would normally eat,” she advises. “Assess how much you’ll actually consume, and adjust the calories and other nutrition information as needed.” A calculator can help compare calories, sugar, fiber and the like, gram for gram, among similar products.

Rule #8: Chill Out

Avoid the sections of the frozen-food aisles populated by sodium-tsunami pizzas, ferociously sweet frozen desserts and boxed entrees with too many unpronounceables. But be on the lookout for stellar additions to a balanced diet: “Frozen fruits and vegetables are a convenient and inexpensive way for people to bump up their intake of much-needed produce,” says Jirbin. Subzero fruits and vegetables can actually be higher in nutrients than their fresh counterparts, because they’re harvested at peak ripeness and are flash-frozen shortly after they’re picked. “They also won’t suffer the same nutrient losses when out-of-season fresh items are transported great distances from farm to store and then stored for some time thereafter.” Be sure clients avoid unwanted extras like syrups or salt.

Rule #9: Don’t Play Games

Supermarkets have their ways to lure shoppers into buying unnecessary items. For example, you’ll want to instruct clients to brush off those so-called “free samples.” Stanford researchers found that nibbling on free food makes it more likely you’ll buy the item, even if it’s something you normally wouldn’t eat.

Major brands pay grocers “slotting fees” for prime eye-level real estate on the shelves. For potentially healthier and cheaper items, look up and down as well. The ends of the aisles are also a home for “end caps”: seasonal kits such as strawberries, whipped cream and premade shortbread cakes that can look oh-so-inviting but are often nutritionally poor choices. Remember to stick to your grocery list!