(RxWiki News) Questions persist about sugar substitutes’ effect on weight—understand the research.

Artificial sweeteners are used in countless “sugar-free” products. They are found in sodas, fruit drinks, candies, baked goods, yogurt, jams, ice cream and other sweetened foods. They are often thought of as weight-loss aids since they have few or no calories. And more people than ever, overweight or lean, are consuming them in “diet” foods and beverages. About 40% of adults and 25% of children in the U.S. consume artificial sweeteners today, which is a large increase from about 20 years ago¹.

The four most popular artificial non-nutritive sweeteners are:

• Aspartame
• Sucralose
• Saccharin
• Acesulfame K

There are also “natural” non-nutritive sweeteners, including stevia and monk fruit extract. They are, however, not quite as natural as many people think, since they often also undergo much processing. For simplicity, we will refer to all of these sweeteners collectively as sugar substitutes.

Can they help you lose weight?

It would seem to make sense that, all things being equal, replacing sugar calories with zero-calorie or very-low-calorie sweeteners would cut your total calories. This calorie reduction then would help with weight loss. And help keep you from gaining weight. But is there evidence that they actually can help people stay thin?

Many studies have sought to answer that question, but have resulted in inconsistent results. Some studies have found that consuming foods and beverages that contain sugar substitutes can indeed help with weight loss. Others suggest that they can contribute to weight gain. Some studies have found no effect on body weight.

The studies have focused on the four most commonly used artificial sweeteners listed above. There’s little research on the effect of the “natural” ones, such as stevia and monk fruit, on weight control.

Why such contradictions?

• Some research suggests that, in the absence of sugar, people may compensate by eating more fat and protein.
• Another idea is that sugar substitutes cause taste distortions. This in turn leads to increased appetite for very sweet, high-calorie foods.
• Or people who consume diet foods may not lose weight because they may reward themselves for the “saved” calories by eating more of those or other foods. This is sometimes called the health halo effect.

There is also emerging evidence, both in lab studies and in people, that sugar substitutes may cause metabolic dysregulation. This causes the the body to increase fat production. This may, at least in part, be due to the sweeteners causing changes in the gut’s bacterial population (the gut microbiota). Sugar substitutes may also have different physiological effects in overweight versus normal-weight people and in people with diabetes.

On the other hand, when sugar substitutes are associated with weight loss, it may not necessarily be because of them.

• People who consume lots of diet foods are often overweight to begin with.
• And when they lose weight, it could be because they take other weight-control steps as well.
• That is, the use of sugar substitutes may simply be a marker for their weight-loss efforts.
• Most studies on these sweeteners are observational (as opposed to clinical trials) and don’t tease this out.

Here are a few examples of the contradictions seen in the research on sugar substitutes.

They can help you lose weight

An analysis of 15 randomized, controlled clinical trials² concluded that using sugar substitutes in place of sugar results in:

• Small weight loss (about 2 pounds, on average)
• Reductions in body fat and waist circumference
• The authors noted that it may also be “a useful dietary tool to improve compliance with weight-loss or weight-maintenance plans.”
• The studies lasted from 3 to 78 weeks and included a total of more than 3,000 people.

They make no difference

• A clinical trial³ found no difference in calorie intake over the course of a day among 30 men who drank sweetened drinks with aspartame, monk fruit, stevia, or sucrose (table sugar). When they drank the diet beverages, they tended to compensate for the calorie savings by eating more food at meals.
• A study⁴ of adolescents found no link between drinking diet sodas and either body weight or body fat. This was after the researchers adjusted for such variables as:
  • Total calorie intake
  • Physical activity
  • Puberty
  • Race
  • Socioeconomic status

They may make you gain weight

A long-term study⁵ found that body mass index (a measure of body weight) was higher among consumers of artificially sweetened beverages than among non-users.

• Those who drank more than 21 such beverages a week were about twice as likely to become overweight or obese as those who consumed none.
• The study noted that the association by itself does not establish causality.
• But it raised a troubling question: Are diet beverages “fueling—rather than fighting—the very epidemic they were designed to block?”

One study found⁶ that in utero exposure to artificial sweeteners may predispose infants to obesity.

• Babies born to women who drank artificially sweetened beverages daily during pregnancy were about twice as likely to be overweight at age one as those born to women who didn’t drink them.
• This was not explained by the mother’s age or calorie intake during pregnancy.
• And the effects were similar in overweight and normal-weight mothers.

Experts weigh in

Despite the contradictory research findings, a scientific statement⁷ concluded that when used wisely, sugar substitutes may help with weight loss or control. But it also concluded that more research is needed. And here’s how the 2015 Dietary Guidelines for Americans sum it up: “Sugar substitutes can help you cut down on calories. But they may not be a good way to manage your weight in the long run.”

Bottom line

It has been surprisingly hard to prove that sugar substitutes help people control their weight.

• In fact, as these products have grown in popularity, Americans have only grown fatter. 
• That doesn’t mean that sugar substitutes are the culprit. So many other factors come into play regarding weight gain and obesity. 
• But it does show they are not the antidote to obesity.

While the weight-control benefits of sugar substitutes may still be unclear, the many health risks associated with high intakes of added sugar are indisputable. In addition, sugar substitutes can be a marker for an unhealthy diet. 

• A better alternative is to cut down on sweetened foods (however they’re sweetened). 
• When thirsty, drink water or plain seltzer instead of diet or regular sodas.

References:

1. Allison Sylvetsky. Journal of the Academy of Nutrition and Dietetics, March, 2017.
2. Paige Miller. American Journal of Clinical Nutrition, September, 2014.
3. S. Tey. International Journal of Obesity, March, 2017.
4. Melissa Laska. Obesity, September, 2012.
5. S. Fowler. Obesity, August,2008.
6. Meghan Azad. JAMA Pediatrics, 2016.
7. American Heart Association and the American Diabetes Association 2012