That Protein Shake Needs a Closer Look. Here’s Why?
- Ryan Fernando
- Jul 24
- 6 min read
Updated: Aug 6
Imagine you are at the gym, feeling great after a hard workout. You mix yourself a delicious vanilla or any flavoured protein shake, but 30 minutes later, you're feeling bloated, a bit sluggish, or strangely hungrier than before. What's going on? It might not be your workout; it could be that "sugar-free" tag on your protein powder.
A few weeks ago, a young software engineer walked into my clinic and said, "I’ve started working out, and I’ve been taking this chocolate-flavoured protein shake daily." "It tastes amazing, but my stomach feels weird, and someone told me it might be artificial sweeteners. Is that true?"
Honestly, this isn’t the first time I’ve heard this question. As a nutritionist for over 20 years, I’ve seen hundreds of clients, gym-goers, teenagers, athletes, and even new moms who’ve turned to protein powders for convenience and muscle recovery. But almost always, their choice is sweetened with something they can't pronounce: sucralose, aspartame, acesulfame-K, or Saccharin.
These sweeteners make your protein shake taste like dessert, but do they come with hidden side effects?
Want to know why and what to choose instead? This blog breaks it down in the simplest way possible.
What Are Artificial Sweeteners, and Where Do They Come From?
Artificial sweeteners are man-made sugar substitutes that give you the sweet taste of sugar. They’re created in laboratories using chemical processes that modify natural molecules or completely synthesise new ones. They are simply sugar in disguise, and you can't even pronounce them properly.
The Most Common Artificial Sweeteners in Protein Powders
The names you often see on supplement labels:
Sucralose: About 600 times sweeter than sugar, heat-stable, and widely used in whey and plant protein powders. It’s made by modifying regular sugar molecules with chlorine atoms. This makes it non-digestible, so it adds sweetness but doesn’t provide energy.
Aspartame: About 200 times sweeter than sugar. It’s made from two amino acids, phenylalanine and aspartic acid, combined with methanol. It’s not heat-stable, so it's less common in baked goods, but still popular in shakes and powders.
Acesulfame Potassium (Ace-K): 200 times sweeter than sugar, often used in combination with other sweeteners like sucralose to cover up any bitter aftertastes. It’s chemically stable and doesn’t break down in your body easily.
Saccharin: Around 300–500 times sweeter, one of the oldest artificial sweeteners used since the early 1900s. It has a slightly metallic or bitter aftertaste.
Neotame: A newer sweetener, 7,000–13,000 times sweeter than sugar. It's chemically related to aspartame but modified to be more stable and safe for those with phenylketonuria (PKU).
Advantame: An ultra-intense sweetener, 20,000 times sweeter than sugar. It’s also derived from aspartame and vanillin (a compound in vanilla). It’s used in very small amounts in the food and beverage industries.
Cyclamate: Banned in the US but still used in some countries. It's 30–50 times sweeter than sugar and often combined with saccharin.
Why Are They So Popular in Protein Powders?
Brands use these sweeteners to make their protein shakes taste like dessert without adding calories or sugar. Because they’re extremely sweet, some are 200 to 20,000 times sweeter than table sugar. That means just a pinch of them can give the same sweetness as teaspoons of sugar, without spiking your blood sugar or adding calories. Sounds like a win-win, right? Well… not always. Especially in products marketed as:
“Sugar-Free”
“Low-Carb” or “Keto-Friendly”
“Zero Added Sugar”
“Weight Loss” supplements
So if you drink chocolate, cookies & cream, or cafe mocha protein shake, and it tastes super sweet without any sugar listed, it’s almost always due to these sweeteners. You’ll usually spot them toward the end of the ingredient list in small quantities.
Here’s an example:
Ingredients: Whey protein isolate, cocoa powder, natural flavours, xanthan gum, sucralose, acesulfame potassium.
That one shake might give you 50–70% of your daily exposure limit, just from one scoop.
Why That Shake Might Bloat You
Your gut is home to trillions of good bacteria, often called your "gut microbiome." These bacteria help digest food, boost immunity, and even influence mood. But some artificial sweeteners can throw this balance off. How?
Sucralose doesn’t get absorbed in your stomach; it passes through your gut. But as it does, it may kill off beneficial bacteria like Lactobacillus and Bifidobacteria (the good guys) and allow harmful species to grow.
This shift can reduce the production of a short-chain fatty acid like butyrate that protects your colon lining. Butyrate is like fuel for your colon lining; without it, these cells weaken and don’t function well. Without enough butyrate, you may feel bloated, gassy, or even constipated. Low butyrate levels are linked to constipation, gas, and IBS-like symptoms.
Saccharin and Neotame have been shown to increase gut permeability, aka “leaky gut,” where toxins may pass into your bloodstream and trigger inflammation.
Does It Mess With Your Fitness Goals?
Artificial sweeteners were designed to help with weight loss and blood sugar control. But the long-term effects are not so black and white.
Frequent artificial sweetener use is linked to a 30–40% higher risk of developing metabolic disorders and type 2 diabetes.
Sucralose, when consumed with carbs (like in a post-workout banana shake), can cause higher blood sugar spikes, the opposite of what you’d want. It may interfere with insulin signalling and gut hormone release.
In simple terms, Sweeteners may confuse your body. You taste “sweet,” your brain expects calories, but none come. Over time, this trains your body to respond poorly to real sugar, affecting insulin, hunger, and fat storage.
Should You Be Worried?
This is the most debated topic. A study found that those who regularly consumed aspartame and acesulfame-K had a 13% higher risk of overall cancer, especially breast and obesity-related cancers.
The study doesn’t prove sweeteners cause cancer, but the association is strong enough to raise concern. Other health authorities like the WHO and EFSA have since started re-evaluating their safety.
Emerging data suggest that daily consumption of sweeteners is linked to:
Increase platelet activity in small human trials, raising concerns about clot formation that could lead to a 34% stroke or heart attack.
17% increased risk of cardiovascular disease (especially in women)
Possible effects on blood vessel health and inflammation markers.
Think of these sweeteners as shortcuts. They “hack” your taste buds, but your body, hormones, and gut may not appreciate it long term.
And if you want to know if "Whey" is healthy or not, check out this video of mine-
And if you want to choose the best whey protein, check out this video-
So now what to do? Switch to Natural Sweeteners
1. Stevia: This is the most common &popular natural sweetener, which comes from the leaves of the Stevia rebaudiana plant, native to South America. It's been used in traditional medicine for centuries and is now one of the most widely used natural sweeteners. Stevia is 200–300 times sweeter than sugar, but has zero calories.
Why choose stevia?
Does not spike blood sugar (great for diabetics and PCOS)
Safe for daily use, approved by the WHO and FDA
Does not harm gut bacteria like artificial sweeteners can
Contains antioxidant compounds like stevioside and rebaudioside-A
Stevia can even improve insulin sensitivity and reduce inflammation.
I switched the diet of a regular gym goer to a stevia-based one, and got noticeable gut effects.
How to use: Choose protein powders or drink mixes labelled "naturally sweetened with stevia". You can also buy liquid stevia drops for home use in tea, coffee, or yoghurt.
2. Erythritol: Erythritol is a sugar alcohol found naturally in some fruits (like pears and grapes) but is usually made via fermentation of glucose. About 70% as sweet as sugar, with almost no calories.
Why choose erythritol?
Very low GI (Glycemic Index = 0) that doesn’t affect insulin or blood glucose
Doesn’t feed harmful gut bacteria like other sugar alcohols (e.g., sorbitol, xylitol)
Best used in small amounts or as part of a blend, like with a breakfast cereal bowl with grapes, a pear, or jamun.
3. Monk Fruit
Monk fruit extract comes from a small green melon native to China. It contains mogrosides, sweet compounds that are 100–250x sweeter than sugar, with zero calories.
Why choose Monk Fruit?
Does not spike blood sugar or insulin
Safe for diabetics and metabolic health
Has anti-inflammatory and antioxidant properties
Mild aftertaste compared to stevia for some users
How to use: Look for blends with monk fruit in protein powders or natural sweetener drops. Great for coffee, shakes, and desserts.
NOTE: Make sure that the quality and the brand are certified and have a clean label.
4. Palm Jaggery (Organic/Unrefined)
Jaggery is a traditional Indian sweetener made by evaporating raw sugarcane juice or palm sap. Unlike refined sugar, it retains minerals like iron, magnesium, and potassium.
Why choose Palm Jaggery (in moderation)?
Less processed than white sugar
Provides small amounts of micronutrients
Has a lower glycemic load when combined with fibre or fat
Useful in traditional recipes and for occasional use
How to use: Use in small amounts in homemade laddoos, warm turmeric milk, or sweet chutneys. Not ideal for diabetics, depending on the blood sugar levels and lifestyle, but better than white sugar for the general population when consumed in a balanced dosage. Remember, the dosage is completely bioindividual and it should be personalised according to the body's needs and condition.
So, before you scoop your next sweet-tasting protein powder, pause and flip the label. Stay scientifically informed.
Want a personalised diet plan to balance your sweet cravings? Click on the link below, and I will help you out.
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