Adding fruit to plain yogurt is a much better option than fruit-flavored yogurt, which often has very little actual fruit and a lot of sugar. (iStockphoto)

It’s amusing that yogurt, which originated as a way to make milk last longer before the days of refrigeration, now makes grocery shopping last longer as we try to make sense of the dizzying selection in the refrigerator case. I regularly get questions from people confused about which yogurt to buy. Here are a few of the most commonly asked, with answers to help you choose more healthfully and get out of the store more quickly.

Nonfat or full-fat?

With so many conflicting headlines about fat these days, it’s no wonder people are stumped when buying dairy products. A key recommendation in the latest Dietary Guidelines for Americans is to choose low-fat or fat-free because dairy fat is mostly saturated, the type linked with increased cholesterol and risk of heart disease. Also, full-fat dairy has more calories than nonfat, so it seems logical that forgoing the fat would be a better choice for keeping weight in check.

But this view has been challenged recently with a few well-publicized studies that surprisingly link the fat in dairy with a lower risk of obesity, heart disease and diabetes. Researchers surmise that full-fat dairy might offer some as-yet-unknown health benefit. It also might help with weight management because the fat in it makes it more satisfying, helping keep your appetite in check.

It’s important to recognize that although these new studies are compelling, they are not conclusive, and more research needs to be done to fully understand dairy fat’s health impact. Until there’s more clarity, I suggest basing your yogurt-buying decisions on two things we do know. First, because unsaturated fats from foods such as nuts and olive oil offer well-documented protective health benefits compared with saturated fat, as well as satiating power, opt for nonfat or reduced-fat yogurt and add healthy fats by topping it with nuts or swirling in some nut butter (which is delicious with fresh fruit). For a savory yogurt dish, add chopped vegetables and a drizzle of olive oil. Second, because calorie for calorie, refined sugar appears to be worse for your health than saturated fat, if faced with a choice between a sugary nonfat yogurt and an unsweetened full-fat option, go for the latter.

Greek or regular?

About a decade ago, Greek yogurt was a treat you could find only at a specialty store. I know firsthand because I was developing recipes back then, and whenever I called for Greek-style yogurt, I had to provide directions for making your own by straining the regular stuff. (It’s actually pretty easy to do. You just put regular yogurt in a fine-mesh strainer that has been lined with a paper towel or cheesecloth, place it in the refrigerator over a bowl and let it sit. After several hours, you remove the thickened yogurt from the strainer and discard the liquid whey that has accumulated in the bowl.)

Now, Greek yogurt dominates the store shelves with dozens of flavors and just about every brand in the game. It has become popular in part because of its luxuriously thick, creamy texture and because it taps into today’s nutritional zeitgeist with more protein and less sugar than regular yogurt.

It has these qualities because with the straining process, the yogurt’s protein is concentrated and some of its naturally occurring sugar (lactose) is drained off with the whey. But on the downside, a lot of nutrients are drained off with the whey, too — more than a third of the yogurt’s calcium, potassium, and zinc. Besides, thickened yogurt’s lower sugar content is not the win you might hope it to be since the sugars inherent in foods such as dairy (or fruit) are not at issue; rather, the problem is the sugar added to foods to make them taste sweet. (More on that in a minute.) The bottom line is that thickened yogurts (Greek or the even-thicker new kid on the block Icelandic Skyr) and regular yogurts offer different culinary and nutritional benefits. Mix it up and enjoy both.

What about sugar?

It’s worth repeating that there’s no need to worry about the sugars that are inherent in dairy products. They’re naturally “packaged” with so many important nutrients that it would be misguided to avoid them. It’s the sweeteners added to these foods that are best kept to a minimum. The problem is it can be hard to tell the difference by looking at the label since the current Nutrition Facts panel lumps all sugars together. (The proposed new label has a separate line for added sugars. I hope it gets past the industry lobbying against it.)

Sure, if a yogurt is packaged with cookie crumbles or candy, it’s a pretty good clue that it should be considered a dessert rather than an everyday, nourishing staple. But sometimes the delineation is not so clear. Many seemingly healthy fruit-flavored yogurts have little actual fruit and nearly as much added sugar as the cookie-packed kind. Your best bet is to get plain yogurt and sweeten it yourself with plenty of fresh, ripe fruit and perhaps a little drizzle of honey. (Ideally, add some nuts, too, as I mentioned.) If you rely on the convenience of the pre-flavored kind, look for a brand that adds 2 teaspoons (8 grams) or less per 6-ounce container. Factoring in the sugar naturally in the dairy, that comes to a ceiling of about 15 grams total sugar for Greek or other thickened yogurt and 22 grams total sugar for regular yogurt.

Krieger is a registered dietitian, nutritionist and author. She blogs and offers a biweekly newsletter at elliekrieger.com. She also writes weekly Nourish recipes in The Washington Post’s Food section.