A container filled with packets of sugar and artificial sweeteners.

Trying to consume less sugar? About 75 percent of American adults are, according to a survey from the International Food Information Council. But that doesn’t mean they’re ready to give up sweet flavors. “We are biologically programmed to like sweet things,” says Nicole Avena, Ph.D., an assistant professor of neuroscience at the Icahn School of Medicine at Mount Sinai in New York City.

Replacing sugar with low-calorie sweeteners, such as aspartame, stevia, and sucra­lose, is one way people attempt to solve this conundrum, but some studies suggest that they might not be better for you than sugar. Where does that leave people who don’t want to go cold turkey on sweetness? Here’s a look at how our bodies respond to sugar and low-cal sweeteners.

Cravings Explained

Our first food—breast milk or formula—is sweet, and humans have evolved to equate sweet tastes with safety, Avena says. For our early ancestors, sweet flavor indicated that a food was okay to eat (bitter foods were more likely to be harmful) and contained calories—important for survival at a time when calories were hard to come by.

More on Sweeteners

Throughout life, we reinforce this preference. Whether it’s cake at a birthday party or ice cream after a bad day, sweet foods are used to celebrate and soothe. Cues in our environment can cause our brains to release the chemical dopamine. “That can trigger a desire to have the food so we feel good,” Avena says.

Combine these tendencies with our modern food environment, where sweet foods are everywhere—and even savory ones, such as tomato sauce and salad dressing, may contain added sweeteners—and you see why kicking sugar is difficult. Humans no longer have to forage for calories, but “our diet is so oversweetened, and we’re drawn to eat pretty much everything,” Avena says.

The Health Toll Sugar Takes

“Sugar is a completely nonessential part of our diets,” says Kimber Stanhope, Ph.D., R.D., a research nutritional biologist in the department of molecular biosciences at the University of California, Davis. The health risks of getting too much added sugars—those added to foods, not the sugars naturally present in foods—are pretty well-established.

For starters, added sugars equal empty calories, providing few if any nutrients. The weight gain that results from consuming excess calories from any source increases the risk of type 2 diabetes, high blood pressure, heart disease, stroke, certain cancers, and more.

And too much added sugar may be harmful even if it doesn’t cause you to put on pounds. It’s also linked to an ­increased risk of type 2 diabetes, fatty liver, and other diseases, Stanhope says. People who ate 25 percent or more of their daily calories in the form of added sugars were more than twice as likely to die of heart disease over the course of 15 years as those who got less than 10 percent of calories from added sugars, regardless of their weight, according to a study published in JAMA Internal Medicine.

That’s why several health authorities advise limiting intake. The Dietary Guidelines for Americans says added sugars should make up no more than 10 percent of your daily calories. That’s about 10 teaspoons (40 grams) for someone eating 1,600 calories. The American Heart Association’s recommendation is even lower—about 6 teaspoons (25 grams) for women and 9 teaspoons (38 grams) for men.

Currently, counting added sugars in your diet isn’t easy, because the Nutrition Facts labels on foods list only total sugars, which includes the natural sugars in foods such as fruit. That will change next January when new regulations for the Nutrition Facts label will go into ­effect. Manufacturers will have to list both.

Low-Cal Sweetener Effects

In advance of those changes and to ­appeal to health-conscious consumers, many food companies are cutting back on sugars in products, according to the market research firm Euromonitor. But that doesn’t always mean they’re making them less sweet.

Manufacturers have long used low-­calorie sweeteners to deliver the sweet hit consumers crave without the sugars or calories; think diet soda and low-cal yogurts. But combining sugar substitutes with sugar in products is an ­approach manufacturers are using more and more to formulate lower-sugar products—and list low added-sugar content on labels—without compromising on the sweetness. This strategy is used even in foods you don’t think of as sweet, such as whole-grain English muffins and vegetable juices.

There’s no question that low-calorie sweeteners provide a sugary flavor without the calories of sugar. But the latest evidence suggests that might not lead to a positive effect on health or weight.

Most recently, a major research review published in BMJ found that the evidence that sweeteners aid oral health, blood sugar levels, or other health problems is extremely limited. While the Food and Drug Administration considers low-calorie sweeteners safe for consumption, some scientists say we don’t have the data to exclude potential harms. Another recent study published in the journal Stroke found that women 50 and older who drank 24 or more ounces (two cans) of diet soda a day were 23 percent more likely to have a stroke than those who drank less than 12 ounces a week. Previous research has linked low-calorie sweeteners to possible heart problems, type 2 diabetes, and potentially harmful changes in the gut microbiome.

As for weight loss, results of studies have been mixed; some have linked low-calorie sweeteners with weight gain. “If used appro­pri­ately, they can be an effective aid for weight management,” says Richard Mattes, Ph.D., R.D., director of the Ingestive Behavior Research Center at Purdue University in West Lafayette, Ind.

But experts say that the types of low-calorie sweeteners may have less in common with each other than many studies have accounted for, and that more ­research is needed. “Everything about them is different, so why do we think we can lump them together?” says Mattes, who is studying how a variety of low-calorie sweeteners behave in the body.

Curbing a Sweet Tooth

Regardless of how different sweeteners affect our bodies, consuming them regularly may play a role in how you eat overall. When people take in less salt and fat, they have what’s called a hedonic shift—in other words, they come to prefer foods that have less salt and fat in them. The research on sugar is evolving, but experts say it’s reasonable to think that sweetness, regardless of the source, would keep us fancying those sweet flavors. “We get accustomed to a certain level of sweetness," Mattes says, "and that becomes our preferred level.” 

What’s more, popular sweet foods—soft drinks, energy drinks, sports drinks, desserts such as cake and cookies, fruit drinks, candy, and dairy desserts—don’t promote health. Lower-­calorie versions of those foods score points for having fewer calories but they aren’t nutritious.

Cutting back on sweeteners altogether may be your best bet to minimize dependence, Avena says. But there are excep­tions. When a little sweetener makes you more likely to eat nutrient-­dense foods—say, oatmeal ­instead of a doughnut for breakfast—it may be worth it. “If you weren’t ­going to eat the oatmeal without the sugar, you’d be doing yourself a ­favor,” Mattes says. The key, regardless of the sweetener, is to not go overboard.

Sugar substitutes may also be helpful as a stepping stone on the way to a more healthful diet, especially in regard to drinks. “The goal isn’t to get people to switch from sugar to diet [drinks],” says Vasanti Malik, Sc.D., a research scientist in the department of nutrition at the Harvard T.H. Chan School of Public Health. “It’s to get people to switch from sugar to water, but diet [drinks or foods] might be an intermediate way to help them.”

Editor’s Note: This article also appeared in the May 2019 issue of Consumer Reports On Health.