Do Zero-Calorie Sweeteners Benefit Your Workout?

Probably not. Exercise is one of those times when sugar--even the added kind--is your best bet.

I read that monk fruit reportedly has antioxidant/anti-inflammatory properties and no calories, but more research is needed. Could it help with workouts and recovery? Be a safe alternative to regular sugar?

- Sugarless in the South Bay

Thanks for the question, Sugarless! Short answer: while monk fruit is probably safe (according to the FDA, at least), it isn’t all that useful for training. Working out and recovering are two of those rare times when the calories from added sugar can be hugely beneficial, so you’re better off using it judiciously rather than avoiding it.

And now, the long answer.

Monk fruit extract is a non-nutritive sweetener derived from the fruit of a plant indigenous to southern China called (obviously) monk fruit—or luo han guo, if you’re fancy.

“Non-nutritive sweetener” means something that adds sweetness but not calories. While monk fruit extract is highly processed, it’s not technically a chemical-based artificial sweetener like sucralose, aspartame, or saccharine. Because of this, it gets a health halo alongside stevia—another “natural” non-nutritive sweetener which comes from the leaves of the stevia plant and is also processed up the wazoo into a white powder you can dump into your cappuccino.

I’m not a fan of non-nutritive sweeteners, whether they come from a forest in Guangdong or a lab in Alabama. I don’t like the idea of tricking my body into thinking it’s getting a nutrient that it’s not getting.

Humans seek out sweetness because, in nature, this is the flavor profile of energy-rich foods like fruit—and we need that energy to survive. It’s only in the last century or so that this sweetness has been isolated into compounds like table sugar and high fructose corn syrup, exploited by the food industry, and dumped down our throats in vast amounts so that it’s become a problem.

In an effort to curb sugar intake without giving up deliciousness, many people consume products filled with zero-calorie, non-nutritive sweeteners.

Your Gut-Brain Axis is too smart for the ol’ sweetness switcheroo.

A 2022 Duke University study suggests this particular slight-of-hand doesn’t really work. The communication network between your mouth, brain, and gut appears to know the body isn’t getting what it needs. Therefore, if your body needs energy, it’s going to continue to crave energy no matter how many diet sodas you drink.

I’m not alone in my disdain. Earlier this year, the World Health Organization issued a slap-down against non-nutritive sweeteners, stating, “There may be potential undesirable effects from long-term use of NSS, such as an increased risk of type 2 diabetes, cardiovascular diseases, and mortality in adults.”

The statement also touched on the point many people care about most: “Replacing free sugars with NSS does not help with weight control in the long term.”

The purported benefits of monk fruit extract.

Monk fruit has been used in Eastern medicine for centuries and there are a few reviews suggesting potential benefits, but they’re vague at best.

The research seems to focus on rodents consuming massive amounts of the stuff, like 100mg per kilogram of body weight or more for weeks at a time. To put that into perspective, one serving of NOW Monk Fruit Extract Powder is 48mg. A 150-pound person consuming the minimum amount used in a 2008 study looking at monk fruit extract’s antioxidant impact on diabetic mice would need to eat 6,800mg daily—for a month.

(They didn’t use this type of extract powder in the study, so those numbers aren’t exact, but you get the point.)

As for the ancient wisdom angle, I question if practitioners of yore utilized the sweetener as we know it, which doesn’t contain the skin or seeds and has been filtered and otherwise processed to accentuate flavor.

If you’re looking for curative benefits, chase down the whole fruit and make some tea.

Exercise goes better with sugar.

While added sugar is often problematic, workouts and recovery are two of those rare times when this type of sugar can be a good thing. To put this into context, I’m talking about long, hard workouts—like over 90 minutes of pushing yourself relatively hard. These long bouts tap your blood sugar and glycogen quickly, so you need fast-absorbing carbs to refill the tank. Otherwise, performance can suffer.

Also keep in mind that, during exercise, your body absorbs sugar through different pathways, so your insulin isn’t impacted as much.

Post-hammerfest, proper nutrition accelerates the recovery process. Key to this are protein and carbs. Protein supplies amino acids to repair muscle. Carbs replenish glycogen stores. Sugar is a carbohydrate, so it’s a good thing in this situation. Monk fruit is not a carbohydrate. It’s not even a nutrient. It supplies nothing.

When not exercising, I prefer to itch my sweet tooth with fruit or moderate amounts of “real” sugar because I understand how sugar works in my body. Unlike non-nutritive sweeteners, the science on sugar’s pros and cons doesn’t pivot every eight months. It’s the devil we know.

 That said, some people aren’t comfortable with added sugar and they have powerful sweet teeth, so they seek out non-nutritive sweeteners. That’s fine and, frankly, I agree that stevia and monk fruit are among the marginally better choices. However, don’t kid yourself into thinking you’re benefiting nutritionally from consuming them.