While it may be tempting to view artificial sweeteners as a guilt-free way to sweeten one’s coffee or tea, the World Health Organization urged people on Monday not to use the sugar substitutes to control weight or avoid certain diseases.

“Replacing free sugars with non-sugar sweeteners (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 news release.

The recommendation applies to “all synthetic and and naturally occurring or modified non-nutritive sweeteners that are not classified as sugars.”

“NSS are not essential dietary factors and have no nutritional value,” Branca added. “People should reduce the sweetness of the diet altogether, starting early in life, to improve their health.”

World Health Organization officials say evidence shows that the popular sweeteners are not effective over the long term when it comes to reducing body fat among adults and children. Furthermore, the WHO says, the study suggests that use of the sweeteners may have “undesirable effects” when used over long periods of time, including the elevated risk of type 2 diabetes, cardiovascular diseases and mortality in adults.

A study released earlier this year found that a sweetener popular in keto diets, erythritol, has been linked to strokes, heart attacks, blood clots, and death.

Branca added that the WHO’s stance is solely meant for people using the sweeteners to lose weight or live a healthier lifestyle.

“This recommendation is not meant to comment on safety of consumption,” Branca told CNN. “What this guideline says is that if we’re looking for reduction of obesity, weight control or risk of noncommunicable diseases, that is, unfortunately, something science [has] been unable to demonstrate.”

The WHO added that the recommendation to avoid NSS does not apply to people with pre-existing diabetes and doesn’t cover personal care products such as toothpaste, skin cream and medications. Low-calorie sugars and sugar alcohols are also not included.

Common sugar substitutes include acesulfame K, aspartame, advantame, cyclamates, neotame, saccharin, sucralose, stevia and stevia derivatives.