Can ‘Diet’ Make You Fat? The Truth About Artificial Sweeteners

Different Types and Their Sweetness

Many artificial sweeteners with differing chemical structures are available.

All are incredibly effective at stimulating the sweet taste receptors on your tongue.

In fact, most are hundreds of times sweeter than sugar, gram for gram.

Some — like sucralose — have calories, but the total amount needed to provide a sweet flavor is so little that the calories you ingest are negligible (1).

Here are the most common artificial sweeteners, their sweetness relative to sugar, and brand names they’re sold under:

Some low-calorie sweeteners are processed from natural ingredients and don’t count as “artificial.”

They’re not covered in this article but include the natural, zero-calorie sweetener stevia, as well as sugar alcohols like xylitol, erythritol, sorbitol, and mannitol.

Effects on appetite

You don’t just eat food to satisfy your energy needs — you also want food to be rewarding.

Sugar-sweetened foods trigger the release of brain chemicals and hormones — part of what is known as the food reward pathway (2, 3, 4).

Food reward is crucial to feeling satisfied after eating and involves some of the same brain circuits as addictive behaviors, including drug addiction (2, 5).

Though artificial sweeteners provide sweet taste, many researchers believe that the lack of calories prevents complete activation of the food reward pathway.

This may be the reason that artificial sweeteners are linked to increased appetite and cravings for sugary food in some studies (6).

However, in other studies, artificial sweeteners did not affect appetite or calorie intake from other foods (7).

For example, in a 2013 study lasting 6 months with 200 people, replacing sugary drinks with either artificially sweetened drinks or water had no effect on food intake (8).

Sweetness and sugar cravings

Another argument against artificial sweeteners is that their extreme and unnatural sweetness encourages sugar cravings and sugar dependence.

This idea is plausible, considering that your flavor preferences can be trained with repeated exposure (9).

While this is not proven specifically in regards to artificial sweeteners, the hypothesis seems plausible. The more sweet foods you eat, the more you may want them.

Impact on body weight

The majority of clinical studies on artificial sweeteners found that artificially sweetened drinks found no significant effects on body weight (10).

However, a 2014 review of nine observational studies noted that artificial sweeteners were associated with a slightly higher BMI — but not with increased body weight or fat mass (11).

More recently, a 2019 randomized controlled trial with 154 participants concluded that both sucrose and saccharin consumption led to an increase in body weight compared to aspartame and rebA, while sucralose users experienced weight loss (12).

According to this study, the type of artificial sweetener makes a difference in body weight.

Other recent studies conclude that artificial sweeteners affect the microbiome leading to decrease satiety, altering glucose production, and are associated with caloric consumption and weight gain. More research on the conncetion between artificial sweeteners and the gut microbiome is needed (13).

It’s important to remember that observational studies cannot prove cause and effect but only allow researchers to find patterns that warrant further investigation.

Nonetheless, the effects of artificial sweeteners on body weight have also been studied in numerous controlled trials, which provide stronger evidence.

Many clinical studies have concluded that artificial sweeteners are favorable for weight control (14).

In a 2023 randomized controlled trial, study participants who consumed beverages sweetened with non-nutritive sweeteners had a 6.3% weight loss compared to the participants who consumed water. The participants who lost weight maintained the weight loss after 40 weeks (14).

A 2014 review of 15 clinical trials found that replacing sugary drinks with artificially sweetened versions can result in modest weight loss of about 1.8 pounds (0.8 kg), on average (11).

Two other reviews led to similar findings (15, 16).

However, newer studies conclude that artificial sweeteners can alter the host microbiome and cause weight weight. In addition, some studies show not all artificial sweeteners cause weight gain, and the type of artificial sweetener appears to make a difference in the results (12, 13).

Effects on metabolic health

Health is about more than your body weight.

Some observational studies link artificial sweeteners to an increased risk of metabolic conditions like type 2 diabetes, heart disease, and metabolic syndrome.

Though observational studies cannot prove cause and effect, the results are sometimes quite staggering.

For example, one 2013 study found that a high intake of diet soft drinks was linked to a 121% greater risk of type 2 diabetes (17).

A 2018 study of 2019 participants without diabetes found that switching to diet soda may not lower the risk of type 2 diabetes because it cannot be ruled out as an independent diabetes risk factor. BMI was a greater factor in a higher risk of type 2 diabetes (18).

Another 2022 review found that artificial sweeteners had an effect on the microbiome in animal and human studies with a negative impact on metabolic health (19).

It’s known that the bacteria in your intestine — your gut flora or microbiome — are incredibly important for health (20).

Whether artificial sweeteners cause problems by disrupting your gut bacteria needs to be studied further, but it appears that there may be some cause for concern.

The bottom line

Recent studies show that consuming artificial sweeteners may result in weight gain due to altering the microbiome.

However, replacing sugar with certain artificial sweeteners may be helpful in reducing body weight — though only slightly at best.

If you use artificial sweeteners and are healthy, happy, and satisfied with the results you’re getting, there’s no need to change anything.

However, if you experience cravings, poor blood sugar control, or other health problems, avoiding artificial sweeteners may be one of many things to consider.