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

Since added sugar is unhealthy, various artificial sweeteners have been invented to replicate the sweet taste of sugar.

As they’re virtually calorie-free, they’re often marketed as weight loss friendly.

Yet, despite increased consumption of these sweeteners — and diet foods in general — the obesity epidemic has only worsened.

The evidence regarding artificial sweeteners is fairly mixed and their use controversial.

This article reviews artificial sweeteners, including their effects on appetite, body weight, and your risk of obesity-related disease.

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.

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.

SUMMARY
There are many different types of artificial sweeteners. The most common ones are aspartame, sucralose, saccharin, neotame, and acesulfame potassium (acesulfame-K).

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.

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

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.

Magnetic resonance imaging (MRI) scans in five men showed that sugar consumption decreased signaling in the hypothalamus, the appetite regulator of your brain.

This response was not seen when participants consumed aspartame — suggesting that your brain may not register artificial sweeteners as having a filling effect.

This implies that sweetness without the calories may lead you to want to eat more food, adding to your overall calorie intake.

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

For example, in a 6-month study in 200 people, replacing sugary drinks with either artificially sweetened drinks or water had no effect on food intake.

SUMMARY
Some researchers believe that artificial sweeteners don’t satisfy people’s biological sugar cravings in the same manner as sugar and could lead to increased food intake. Still, the evidence is mixed.

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.

For example, reducing salt or fat for several weeks has been shown to lead to a preference for lower levels of these nutrients.

Sweetness is no different.

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.

SUMMARY
The strong sweetness of artificial sweeteners may cause you to become dependent on sweet flavor. This could increase your desire for sweet foods in general.

Impact on Body Weight

Several observational studies on artificial sweeteners found that artificially sweetened drinks are linked to weight gain rather than weight loss.

However, a recent 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.

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.

In one large, 18-month study in 641 children aged 4–11, those drinking 8.5 ounces (250 ml) of an artificially sweetened drink gained significantly less weight and fat than children who consumed a sugary drink.

Another 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.

Two other reviews led to similar findings.

Thus, evidence from controlled studies suggests that artificial sweeteners don’t cause weight gain and may even be mildly effective for weight loss.

SUMMARY
Some observational studies link artificial sweeteners to weight gain, but evidence is mixed. Controlled studies suggest that artificially sweetened drinks don’t cause weight gain and may even aid weight loss.

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 study found that a high intake of diet soft drinks was linked to a 121% greater risk of type 2 diabetes.

Another study noted that these beverages were associated with a 34% greater risk of metabolic syndrome.

This is supported by one study on the effects of artificial sweeteners on both mice and humans. It associated the sweeteners with glucose intolerance and a disruption in gut bacteria.

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

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.

SUMMARY
Artificial sweeteners have been tied to an increased risk of metabolic problems. However, more studies are needed before any strong conclusions can be reached.

The Bottom Line

Consuming artificial sweeteners does not appear to cause weight gain — at least not in the short term.

In fact, replacing sugar with 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.