Trying to lose weight? Avoid sugar substitutes, the World Health Organization warns

By Katie Kindelan

People who are trying to lose weight should avoid using zero calorie non-sugar sweeteners, according to a new recommendation released Monday by the World Health Organization.

Zero calorie non-sugar sweeteners, including artificial and natural sweeteners like aspartame and stevia, have not been shown to help with weight loss long-term in children or adults, and their use may bring side effects like increased risk of cardiovascular diseases, Type 2 diabetes and death in adults, the WHO said in its finding.

"Replacing free sugars with NSS does not help with weight control in the long term. People need to consider other ways to reduce free sugars intake, such as consuming food with naturally occurring sugars, like fruit, or unsweetened food and beverages," Francesco Branca, WHO director for nutrition and food safety, said in a statement announcing the recommendation. "NSS are not essential dietary factors and have no nutritional value. People should reduce the sweetness of the diet altogether, starting early in life, to improve their health."

The WHO defines artificial sweeteners as "all synthetic and naturally occurring or modified nonnutritive sweeteners that are not classified as sugars found in manufactured foods and beverages, or sold on their own to be added to foods and beverages by consumers."

The only exception to the recommendation, according to the agency, is for "individuals with pre-existing diabetes."

The WHO said it issued the recommendation after a "systematic review" of over 280 studies involving the use of artificial sweeteners in adults, pregnant women and children.

Due to a growing obesity epidemic worldwide, non-sugar sweeteners are becoming increasingly common ingredients found in soft drinks, "diet" foods and other processed products. Although federal regulatory agencies like the U.S. Food and Drug Administration have deemed most artificial sweeteners to be safe, little is known about the long-term health effects.

Low-calorie sugar alternatives have been found in at least one study to change the gut microbiome, the collection of microbes in the gut that help protect humans against disease and enable us to digest food.

Saccharin, sucralose, aspartame and stevia were the four substances tested in the study on gut health, published last year in the medical journal Cell.

Overall, the healthiest sweetener to use is no sweetener at all. The American Heart Association recommends drastically lowering added sugar in a daily diet to help slow the risk of obesity and heart disease and to focus on more whole foods like a wide variety of fruits and vegetables.

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Close-up of a spoon with sugar on a table.

"Our cells need glucose to function, so it's not totally evil," Dr. Jennifer Ashton, ABC News chief medical correspondent, said of sugar. "But I can tell you, even with things like bread, yogurt, which can be healthy, they can be loaded with added sugars, so that's the number that I encourage people to look at on the label."

The U.S. Dietary Guidelines currently recommend that Americans ages 2 and older limit their intake of added sugars to less than 10% of their daily calories, or about four tablespoons for someone consuming a 2,000-calorie diet. Children under the age of 2 are advised to consume no added sugars at all in their diet.

The average American consumes around 34 teaspoons of sugars a day, which equals over 500 calories, according to the U.S. Department of Agriculture.

People who are overweight or obese are at an increased risk for many serious health conditions, including cancer, heart disease, stroke, high blood pressure, gall bladder disease, osteoarthritis, mental illness and other health problems.