Zero-Calorie Sweeteners and Weight: The WHO Guideline Explained

Swapping sugar for a zero-calorie sweetener sounds like an easy win for weight. In 2023 the World Health Organization looked at the evidence and came to a more cautious view. This guide explains what the guideline says, why it is labeled “conditional,” and what a reasonable reader can take from it. It is general education, not medical advice.

What the WHO recommended

In May 2023 the WHO issued a guideline on non-sugar sweeteners, the group that includes artificial sweeteners and many plant-derived ones sold on their own or added to foods and drinks. It recommends against using them to control body weight or to reduce the risk of non-communicable diseases. It says the recommendation applies to everyone except people who already have diabetes, and it is a “conditional” recommendation.

The review’s conclusions

The guideline rests on a systematic review of the available research that covered hundreds of studies. Two findings stand out:

• No long-term benefit for body fat. Across trials, using non-sugar sweeteners did not show a lasting reduction in body fat in adults or children.
• Possible downsides in observational studies. Long-term use was linked to a higher risk of type 2 diabetes, cardiovascular disease and earlier death in adults.

Why “conditional” matters

A conditional recommendation means the evidence is not strong enough to be certain and the right choice may depend on the person. The WHO explained that the links to disease could be affected by confounding. People who are already gaining weight or have higher health risks may be more likely to choose diet drinks, which can make the sweeteners look harmful when they are partly a marker of something else.

What critics say

Some researchers have argued the guideline deserves reconsideration. Their points include the quality of the underlying studies, short-term trials where replacing sugary drinks with diet versions did help, and the fact that the best comparison for most people is not “sweetener or nothing” but “sweetener or sugar.” The disagreement is a reason to read headlines carefully rather than a reason to dismiss the guideline.

What this means in practice

• Sweeteners are not a weight-loss tool. The evidence does not support relying on them to lose weight or keep it off.
• Sugar-sweetened drinks still add calories quickly. Switching to a diet version may reduce calories in the short term for some people. The WHO’s point is about long-term control, not that one swap cancels the other.
• Water and unsweetened drinks are the simple default. Over time, gradually lowering your preference for very sweet flavors may matter more than which sweetener you use.
• Check labels. Sweeteners show up in foods people do not expect, from yogurt to sauces. Our guide to reading a nutrition label in five minutes shows where to look.
• If you have diabetes, the guideline does not apply to you; ask your care team what fits your plan.

For more on how processed foods affect eating, see ultra-processed foods and weight.

Final thoughts

The WHO does not say sweeteners are dangerous in a typical amount, and it does not say they are useless in every case. It says the evidence does not support using them as a weight-control strategy. A balanced reading is to treat them as a personal preference, not a plan.

Sources

• World Health Organization, Use of non-sugar sweeteners: WHO guideline, 2023.
• WHO news release, “WHO advises not to use non-sugar sweeteners for weight control in newly released guideline,” 15 May 2023.
• Pan American Health Organization summary of the WHO guideline, May 2023.
• “WHO guideline on the use of non-sugar sweeteners: a need for reconsideration.” Commentary published in 2023 (PMC10630128).