If you’re trying to choose between diet soda and regular soda for blood sugar or liver health, the ingredient differences matter. While diet soda doesn’t spike your blood sugar like regular soda, studies on both beverages raise questions about their impact on liver health.
If blood sugar is your primary concern, diet soda is the better option in the short term.
Regular soda is high in added sugar or high-fructose corn syrup, which is quickly absorbed after you drink it.
- Sugar, or fructose, is quickly digested and enters the bloodstream, causing blood sugar levels to spike.
- In response, your pancreas releases insulin, a hormone that helps move sugar out of the blood and into cells, where it can be used for energy or stored for later.
- People with insulin resistance, a condition where cells don’t respond to insulin to move sugar out of the blood, can experience bigger spikes. The pancreas releases more insulin to lower blood sugar levels, further straining metabolism. High intake of sugar-sweetened beverages has been associated with insulin resistance, which increases the risk of type 2 diabetes and even heart disease.
Diet sodas contain little to no sugar. They’re typically sweetened with artificial or non-nutritive sweeteners, such as aspartame or sucralose, which don’t raise blood sugar levels. As a result, diet soda generally doesn’t trigger the same fast rise in blood sugar or insulin.
Diet Soda Could Still Increase Health Risks
That said, the long-term effects of artificial sweeteners remain unclear. Some research suggests that consistently drinking diet sodas can influence appetite, gut microbiome composition, or insulin sensitivity, all of which can indirectly affect blood sugar and metabolic health.
Some research has found that both types of sodas are associated with an increased risk of type 2 diabetes.
Overall, diet soda helps limit short-term blood sugar spikes, but regular daily intake of any soda may still affect metabolic health over time.
The high sugar content in regular soda is linked to fat build-up in the liver, but some evidence suggests diet soda isn’t entirely harmless for liver health either.
One reason regular soda is especially concerning is its fructose content. Fructose is processed mostly by the liver, and when too much is consumed, it can be turned into fat.
Over time, this process can lead to metabolic dysfunction–associated steatotic liver disease (MASLD), formerly known as fatty liver disease. MASLD occurs when excess fat builds up in the liver and can progress to liver inflammation, scarring, and even serious liver damage.
However, some research now suggests that diet soda may not be without risks to the liver:
- Studies link both regular and artificially sweetened sodas to liver inflammation and fat accumulation, compared with little or no intake.
- In a large study presented at a medical conference, people who drank more sugar-sweetened beverages had a higher risk of MASLD. The same study also found a higher risk among people who regularly drank low- or no-sugar beverages, such as diet soda, though these findings are based on an unpublished conference report.
These studies are observational, which means they can’t prove cause and effect. Still, they suggest a potential association between frequent soda consumption of any kind and the risk of liver disease.
Diet and regular sodas may affect more than blood sugar and liver health:
- Weight management: Regular soda adds empty calories that can contribute to weight gain. Although diet soda eliminates calories, some studies suggest certain artificial sweeteners may affect appetite or hunger signals and are linked to more body fat.
- Cardiometabolic risk: Regular soda’s added sugars are linked to a higher risk of type 2 diabetes and cardiovascular disease. Research on diet soda is mixed, as some studies show no clear effect on metabolic health, while others link frequent intake to a higher risk of heart disease.
- Dental health: Both regular and diet sodas are acidic, which can harm tooth enamel. Regular soda also increases the risk of cavities due to its sugar content.
This comparison uses Coca-Cola products as an example. Calories, sugar content, and the type of artificial sweetener can vary by brands.
Regular Soda (12-ounce can of Coke)
Diet Soda (12-ounce can of Diet Coke)
Calories
138
0
Carbohydrates
39g
0
Added sugar
39 g
0
Other sweeteners
0
Aspartame
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U.S. Department of Agriculture: FoodData. Central. Coca Cola, Cola
U.S. Department of Agriculture: FoodData. Central. Diet Coke Can, 12 fl oz
