Does Aspartame Help Manage Weight?

A dietitian lends her expertise.

Medically reviewed by Allison Herries, RDN

Aspartame is an artificial, nonnutritive sweetener used worldwide as a food additive in more than 6,000 products. It tastes twice as sweet as table sugar but contributes minimal calories to foods and beverages.

Despite its widespread use, aspartame is controversial. It has been studied for its impact on health, namely blood sugar and weight management. Still, research on aspartame's health benefits and safety continues to evolve.

The following article covers the uses of aspartame, its nutritional value, and safety considerations.

What Is Aspartame?

Aspartame is an artificial sweetener 200 times sweeter than table sugar (sucrose). It does not provide significant calories, so it is considered a noncaloric or nonnutritive sweetener. However, foods with aspartame may still be high in calories depending on their other ingredients.

Aspartame was discovered in 1965. The U.S. Food and Drug Administration (FDA) first approved aspartame in 1974 for chewing gum, packaged dry foods, and as a table sweetener. In 1996, the FDA expanded aspartame’s approval for general use.

Aspartame is made of methanol, and the two proteins (amino acids) aspartic acid and phenylalanine.

Phenylalanine regulates chemical messengers that send signals between nerves and cells (neurotransmitters). Aspartic acid is a neurotransmitter.

Ingesting methanol from contaminated beverages or methanol-containing products like household cleaning supplies is poisonous. However, methanol from fruits, vegetables, and aspartame is not harmful.

Safety Profile

The FDA regulates artificial sweeteners. The FDA categorizes aspartame as "generally recognized as safe" (GRAS) and has approved its use as a food additive.

Despite recent concern for the cancer-causing effects of aspartame, research yields conflicting results.

Some studies show a potential association between aspartame and liver cancer. Another study observed an increased risk of developing any type of cancer, breast cancer, and obesity-related cancers with a higher intake of aspartame.

Still, other studies did not identify a correlation between lymphoma, leukemia, or brain cancer during a five-year follow-up period.

Even health governing bodies and food regulation organizations disagree on the safety of aspartame.

In 2023, the World Health Organization (WHO) and the International Agency for Research on Cancer (IARC) classified aspartame as possibly cancer-causing (carcinogenic) to humans based on limited research.

Notably, the classification is based on whether something can cause cancer, not how likely it is to cause cancer.

Still, other organizations have found the evidence linking aspartame to cancer inconclusive. The Joint Food and Agriculture Organization (FAO)/WHO Expert Committee on Food Additives (JECFA), the FDA, and the European Food Safety Authority (EFSA) concluded that aspartame is safe within its current common uses.

How Much Aspartame Is Safe?

The acceptable daily intake (ADI) set by the FDA is 50 milligrams of aspartame per kilogram of body weight per day (mg/kg bw/d) or about 22.5 mg per pound of body weight per day. The ADI for someone weighing 150 pounds would be 3,409 mg or 3.4 grams (g) of aspartame daily.

EFSA and JECFA set the ADI slightly lower at 40 mg/kg bw/d (around 18 mg per pound of body weight per day). For someone weighing 150 pounds, the ADI would be 2,727 mg or 2.3 g of aspartame daily.

A can of diet soda contains 200 mg to 300 mg of aspartame. A 150-pound person would need to consume eight to 12 diet sodas daily to meet the ADI established by EFSA and JECFA. Using the FDA cutoffs, drinking 10 to 15 diet sodas per day would meet the ADI for that same person.

Side Effects

There are no known serious immediate side effects of aspartame. Aspartame does not cause any gastrointestinal issues.

Uses of Aspartame

In some situations, using aspartame is beneficial. In other instances, aspartame use merits caution.

Impact on Blood Sugar

Aspartame does not impact insulin or glucose levels following a meal. Moreover, unlike table sugar, aspartame does not require insulin for metabolism and uptake into cells.

However, whether aspartame’s lack of effect on glucose levels is clinically meaningful is unclear.

One meta-analysis found no difference in blood sugar levels between aspartame, a placebo, or sucrose. The study observed no benefit to using aspartame instead of table sugar for managing blood sugar. Conversely, the researchers suggested there was no harm in consuming aspartame.

Despite conflicting evidence, aspartame appears to be a suitable sugar alternative for people monitoring blood sugar. Still, more research is necessary to understand aspartame’s impact on blood sugar.

Weight Management

Evidence regarding aspartame’s effect on weight is mixed.

Randomized controlled trials do not show a link between aspartame and decreases in body mass index (BMI) or weight. Aspartame’s influence on waist circumference (a proxy for abdominal fat) among people who are overweight is inconsistent.

Conversely, studies that follow a group of people over time (a cohort) noted increased BMI, weight, and waist circumference.

Aspartame’s impact on weight management may not be apparent for years. The cohort studies evaluated had an average follow-up period of 10 years.

Weight gain from artificial sweeteners may be due to their impact on eating habits. Artificial sweeteners alter brain signaling associated with appetite and energy balance.

Yet again, the research conflicts. According to one meta-analysis, aspartame does not influence levels of ghrelin, the hormone associated with hunger.

Still, other research shows consuming aspartame instead of sucrose reduces body weight. Aspartame contains fewer calories than regular sugar. So, using aspartame instead of table sugar results in a lower calorie (energy) intake, contributing to weight loss.

Adding to the confusion, the Academy of Nutrition and Dietetics (AND) supported aspartame for weight management but concluded it does not affect appetite or food intake.

More long-term research is necessary to understand the link between aspartame and weight.

Dental Health

Sugar acts as a food source (substrate) for oral bacteria. Oral bacteria cannot metabolize certain alternative sweeteners like xylitol. Those sweeteners are protective against dental caries (cavities). Research is still determining the role of aspartame in dental health.

Some of the bacteria in the mouth, such as Streptococcus mutans (S. mutans), are associated with dental plaque and the development of cavities.

One in vitro study found that aspartame caused less plaque than sucrose. Moreover, aspartame prevented the growth of S. mutans.

However, aspartame is acidic. Acidic foods break down tooth enamel. Aspartame increases the acidity of plaque and contributes to enamel erosion.

Another in vitro study revealed that diet cola containing aspartame changed tooth enamel. However, the study used diet cola instead of another aspartame product. Diet cola contains phosphoric and citric acid, which erode tooth enamel.

Additional human studies are required to determine the dental health benefits of aspartame.

Neurological and Psychological Effects

Aspartame’s chemical composition and properties suggest an impact on neurological and psychological outcomes.

Research indicates aspartame can cross the blood-brain barrier to affect neurotransmitters such as dopamine and serotonin.

Additionally, aspartic acid that crosses the blood-brain barrier is associated with the deterioration of neurons. Neuronal breakdown contributes to cognitive impairment, mood changes, and headaches and migraines.

Despite the plausible connection, the evidence has yielded mixed results on aspartame’s neurological and psychological effects.

According to one review, consuming high doses of aspartame (900 to 3,000 mg/kg bw/d) increases headaches in people susceptible to migraines. However, other research notes that consuming aspartame within the ADI does not affect headache duration or intensity.

Again, controversy exists as to aspartame’s effect on depressive symptoms. Some research shows severe depression symptoms appeared with 30 mg/kg (around 14 mg per pound) bw of aspartame daily. Other studies observe no increase in depression with a standard dose of aspartame.

Interestingly, one randomized controlled trial found aspartame may increase depression at a lower dosage: 25 mg/kg (around 11 mg per pound) bw/d. Compared to participants assigned 10 mg/kg (around 4.5 mg per pound) bw/d of aspartame, those receiving the higher dosage reported greater levels of depression and irritability.

Again, more research is necessary. However, small doses of aspartame (below the ADI) may not be associated with adverse neurological and psychological effects.

How to Use Aspartame

Aspartame exists in soft drinks, dessert mixes, yogurt, instant puddings, chewable vitamins, and breakfast cereals.

Aspartame is stable in dry conditions. When exposed to moisture, aspartame breaks down, resulting in reduced sweetness.

Likewise, aspartame more readily disintegrates in liquid and acidic environments. After about 50 weeks of storage at room temperature, aspartame in diet soda degrades.

Baking with aspartame is not recommended because of its instability at high temperatures and in moist environments.

Equal is a common sugar brand that contains aspartame. You can purchase it at the grocery store for use at home in desserts or added to coffee for sweetness.

Aspartame vs. Stevia

Unlike aspartame, an artificial sweetener, stevia is a natural, plant-based sweetener. It is derived from steviol glycosides, compounds from the leaves of the Stevia rebaudiana (Bertoni) plant native to South America.

Stevia is a nonnutritive (which means it doesn't contain calories) sweetener that is 200 to 400 times sweeter than table sugar, depending on how much steviol glycoside is in it. Therefore, stevia can be as sweet as or sweeter than aspartame.

Stevia, like aspartame, also does not elicit a blood sugar or insulin response. As a result, it is safe for use by people with diabetes. Moreover, some studies reveal that stevia reduces blood sugar levels. However, people taking diabetes medication may experience side effects after consuming stevia (such as low blood sugar levels).

Some research indicates no difference between stevia and aspartame or stevia and sucrose in terms of feelings of fullness (satiety) and calorie intake.  However, other research has found that participants consumed less food and fewer beverages after drinking stevia than they did after drinking water.

Still, more research is necessary to determine the effects of stevia and how it compares to aspartame.

Like aspartame, stevia itself is not associated with any gastrointestinal side effects.

The FDA approved steviol glycosides for use. Although stevia leaf and raw extracts are available as supplements, the FSA has not approved their use as sweeteners. Supplements are also unregulated.

When purchasing stevia, look for products listing specific glycosides: rebaudioside A (Reb A), stevioside, or rebaudioside D (Reb D).

Is Aspartame Good for Me?

There are several factors to consider when deciding whether aspartame is for you.

Allergy: Avoid aspartame if you're allergic to it or its components. Seek immediate medical attention if you have a severe allergic reaction to it (e.g., itching, hives, shortness of breath).

Kidney toxicity: Consuming large amounts of aspartame (more than the ADI established by the FDA and EFSA) may be toxic to the kidneys, but further research is necessary.

People with the following conditions should avoid or greatly limit the use of aspartame:

• Phenylketonuria (PKU): The genetic condition PKU affects the ability to metabolize phenylalanine. People with PKU should limit or avoid aspartame.

• Migraines, epilepsy, or neuropsychiatric issues: People with these conditions may want to limit aspartame because of its potential effects on mood and brain health. However, additional long-term studies are necessary.

Pregnancy: The FDA and AND have stated that aspartame is safe during pregnancy. Still, people who are pregnant should limit aspartame to one to two servings daily—well below the ADI.

Weight loss: Despite good intentions to reduce calorie intake, it remains to be seen whether nonnutritive sweeteners like aspartame result in calorie reduction and weight loss. One research theory suggests that separating the sweet taste from the calorie content influences hormones that impact metabolism. Still, aspartame may be a reasonable alternative for people seeking a sweetener with minimal glycemic impact.

Overall, evidence suggests aspartame is not associated with adverse health effects. Still, additional research to better understand aspartame's role in health would be beneficial.

Summary

Aspartame is a good sweetener alternative for people with diabetes. However, aspartame’s effects on appetite and weight remain unclear.

Aspartame can be part of your eating habits. If you choose to consume it, try to stay within the recommendations established by the FDA, which are less than 50 mg/kg (around 22.5 mg per pound) bw daily.

Talking with a healthcare provider or registered dietitian can help you distinguish myth from fact when it comes to aspartame and decipher whether this artificial sweetener is safe for you.

Read the original article on Verywell Health.