Quick Answer
Most sugar free sweeteners do not contain calories or spike insulin, so they will not technically “break” a fast. However, some people find that these sweeteners may increase cravings during a fast, so they prefer to avoid them.
Do Sugar Free Sweeteners Have Calories?
Most sugar free sweeteners contain very few or zero calories. For example:
| Sweetener | Calories per Serving |
|---|---|
| Stevia extract | 0 calories |
| Sucralose | 0 calories |
| Aspartame | 4 calories |
| Saccharin | 0 calories |
| Xylitol | 9.6 calories |
| Erythritol | 0.2 calories |
Since they contain minimal or no calories, sugar free sweeteners will technically not break a fast.
Do Sugar Free Sweeteners Spike Insulin?
Insulin is the hormone that allows sugar to enter your cells. When insulin levels are high, your body is in a “fed” state. To get the full benefits of fasting, insulin levels need to be low.
Most sugar free sweeteners have minimal effects on insulin levels. The exceptions are sugar alcohols like xylitol, sorbitol, and maltitol. Sugar alcohols can raise insulin slightly, although not nearly as much as regular sugar.
So while most sugar free sweeteners won’t spike insulin to any significant degree, the sugar alcohols may cause a slight insulin response. But the effect is small enough that it likely won’t disrupt the overall metabolic benefits of fasting.
Do Artificial Sweeteners Increase Appetite and Cravings?
Some people report that sugar free sweeteners increase hunger levels and cravings during a fast. There are a few potential reasons for this:
– Psychological effect – the sweet taste may trigger the desire for actual sugar.
– Alteration of gut bacteria – artificial sweeteners may feed harmful gut bacteria that release chemicals that increase appetite.
– Blunting of sweet taste receptors – regular use of artificial sweeteners may reduce sensitivity to sweet tastes, increasing cravings for overly sweet food.
– Increase in insulin resistance – some studies link artificial sweeteners to insulin resistance, which can amplify hunger hormones.
The evidence is mixed on whether non-caloric sweeteners actually increase appetite and cravings. But if you personally notice this effect, it may be best to avoid sugar free sweeteners when fasting. Pay attention to your body’s signals.
The Bottom Line
Sugar free sweeteners will technically not break a fast since they do not contain calories or significantly spike insulin.
However, some people find that these sweeteners increase food cravings and appetite during a fast. If you notice this effect, avoid them. But if you can consume them without any increase in hunger, then they should be fine when fasting.
Some sugar alcohols like xylitol and maltitol may have a mild effect on insulin, but not enough to disrupt fasting. Overall, sugar free sweeteners are unlikely to reverse the key metabolic benefits of fasting such as ketosis and low insulin levels. But as with anything, individual responses vary. Pay attention to your body and discontinue use of sweeteners if you have an adverse response.
Do Sugar Alcohols Break a Fast?
Sugar alcohols are considered “lower carb” sweeteners as they are not fully digested and absorbed by the body. The most common ones are:
– Xylitol
– Sorbitol
– Maltitol
– Isomalt
– Lactitol
– Mannitol
– Erythritol
Do these sugar alcohols break a fast?
They have minimal effects on insulin compared to regular sugar, so most of them will not disrupt ketosis or other fasting benefits.
However, some sugar alcohols can mildly impact insulin:
– Xylitol has the greatest effect, raising insulin levels slightly comparable to glucose.
– Maltitol comes in second in terms of insulin effect.
– Sorbitol ranks third.
Therefore, it’s best to minimize xylitol, malitol, and sorbitol during a fast. The other sugar alcohols like erythritol, mannitol, and lactitol have negligible effects on insulin and can be consumed without concern about breaking a fast.
Glycemic Index of Sugar Alcohols
The glycemic index (GI) measures how much a food raises blood sugar. Pure glucose has a GI of 100.
Here is the GI for various sugar alcohols:
| Sugar Alcohol | Glycemic Index |
|---|---|
| Xylitol | 13 |
| Maltitol | 36 |
| Sorbitol | 9 |
| Erythritol | 0 |
| Isomalt | 2 |
| Lactitol | 6 |
| Mannitol | 0 |
As you can see, xylitol and maltitol have the highest GI, while the others have minimal impact.
So in summary:
– Xylitol, maltitol, and sorbitol can mildly impact insulin and blood sugar.
– Erythritol, isomalt, lactitol, and mannitol will not affect insulin or blood sugar.
To be on the safe side during a fast, minimize consumption of xylitol, maltitol and sorbitol. The other sugar alcohols are less likely to disrupt ketosis or other fasting benefits.
Stevia and Monk Fruit: The Best Sugar Free Sweeteners for Fasting?
Stevia and monk fruit are natural sugar free sweeteners. Here is how they compare to artificial sweeteners during a fast:
Stevia
Stevia comes from the leaves of the stevia plant. It contains zero calories and has virtually no effect on blood sugar or insulin levels.
Of all the sugar free sweeteners, stevia is likely the most ideal for fasting. There is no evidence it disrupts ketosis or increases hunger and cravings.
Monk Fruit (Luo Han Guo)
Monk fruit is a small melon that contains natural sweet compounds called mogrosides. Like stevia, it has no calories or carbs and does not impact blood sugar or insulin.
Monk fruit may also be an optimal choice for fasting. However, beware of monk fruit products that contain added sugar alcohols like erythritol which could affect some people.
Overall, stevia and monk fruit products without added ingredients may be the best options while fasting as they are unlikely to impact ketosis or appetite.
Can You Have 0 Calorie Energy Drinks While Fasting?
Many 0 calorie energy drinks contain sugar free sweeteners as well as stimulants like caffeine.
Here’s how these energy drinks may impact fasting:
Sugar Free Sweeteners
Most 0 calorie energy drinks are sweetened with sucralose (Splenda), aspartame, or acesulfame potassium (Ace-K). As mentioned earlier, these have minimal or no effect on insulin and blood sugar and are unlikely to interfere with ketosis or other fasting benefits.
Avoid energy drinks with sugar alcohols like maltitol, sorbitol, and xylitol as they may have a slight impact.
Caffeine and Other Stimulants
Caffeine and similar stimulants can enhance energy, focus, and alertness during a fast. Moderate caffeine intake from 0 calorie energy drinks is unlikely to have any negative impacts.
However, too much caffeine may cause side effects like anxiety, insomnia, digestive issues, and heart palpitations in some people. Limit caffeine to 400mg per day or less.
Excessive intake of 0 cal energy drinks could also potentially spike appetite and cravings in some individuals, so portion control is key.
Artificial Food Dyes
Some scientists believe artificial food dyes found in certain energy drinks may adversely alter gut bacteria and even behavior in children.
While more research is needed, it may be wise to avoid energy drinks with artificial colors, especially blue dye #1 and red dye #40. Look for products without artificial dyes.
The Verdict
In moderation, 0 calorie energy drinks are unlikely to break a fast or disrupt ketosis thanks to their sugar free sweeteners and lack of calories.
However, limit caffeine to avoid side effects. Also avoid artificial dyes if possible. And as with any food, pay attention to your body’s signals as some people may experience increased hunger or cravings.
What Can You Drink During a Fast?
Some beverages are better choices than others for fasting:
Water
Staying hydrated with water is vital. Add slices of lemon, lime, cucumber or mint for flavor variety if desired.
Tea and Coffee
Caffeinated and herbal teas are excellent for fasting. Green tea provides antioxidants. Black coffee is also fine.
Bone Broth
Sipping on bone broth provides electrolytes like sodium and potassium. Opt for low calorie, low-carb options.
Apple Cider Vinegar
Small amounts of apple cider vinegar mixed with water may suppress appetite.
Minerals
Sodium, magnesium and potassium supplements can replenish electrolytes lost while fasting.
Fasting Salts
Special blends provide sodium, potassium and magnesium tailored for fasting.
Carbonated Water
Sparkling waters like seltzer, club soda or mineral water are refreshing low-calorie options.
The main beverages to avoid are caloric drinks like juice, soda, alcohol, and any sweetened coffees or teas. Limit milk to small amounts. Overall, stick with zero or very low calorie unsweetened beverages.
Intermittent Fasting and Sweeteners: What the Research Says
Here’s a look at some of the current research on using sweeteners during intermittent fasting windows:
Rat Studies on Artificial Sweeteners During Fasting
Some rat studies have found that consuming artificial sweeteners like saccharin during fasting windows can interfere with ketosis and other metabolic processes.[1]
However, rat metabolism differs greatly from humans so these results may not apply. Human research is needed.
Human Study on Aspartame and Insulin
A study had participants consume either capsules of aspartame (artificial sweetener) or glucose after a 12 hour overnight fast.
Both aspartame and glucose increased insulin levels. But insulin rose 3 times higher in response to glucose compared to aspartame.[2]
This suggests aspartame has a minor effect on insulin. So while it may not disrupt fasting benefits entirely, effects likely depend on the individual.
Sucralose and Blood Sugar Control During Fasting
One study had participants do intermittent fasting combined with either sucralose (Splenda), stevia, or sugar sweetened beverages.
Both the sucralose and stevia groups had better blood sugar control compared to those consuming sugar. But stevia showed marginally better results than sucralose.[3]
This indicates sucralose does not interfere with blood glucose management during intermittent fasting. But stevia may be slightly better for optimal fasting effects.
More Human Research is Needed
Overall the human studies are limited. More are needed to determine individual responses to sweeteners during fasting periods.
Until more evidence is available, the best option is to pay attention to your body. Avoid sweeteners if you notice increased hunger or cravings when fasting.
Conclusion
Sugar free sweeteners will not technically “break” a fast since they do not contain calories or significantly raise insulin levels.
However, some people may experience increased hunger and cravings from artificial sweeteners and sugar alcohols. Avoid these if you have this response.
Natural sweeteners like stevia and monk fruit are less likely to affect fasting compared to artificial sweeteners.
Beverages with zero calories and sweeteners like coffee, tea, seltzer and diet sodas will not break your fast. Limit caffeine and artificial ingredients if possible.
Current research on sweeteners and intermittent fasting is limited. Listen to your body’s signals and discontinue sweeteners if you have any adverse effects.
At the end of the day, focus on how you feel rather than obsessing over sweeteners. Your experiences and the effects on your body should guide your fasting regimen.
