Why Your “2g Net Carbs” Protein Bar Is Probably Lying to Your Face
That protein bar sitting in your pantry the one with “2g net carbs!” splashed across the front in triumphant letters? Yeah, it might actually be 8g. And that sneaky little difference could be exactly why your keto progress hit a wall while you’ve been doing “everything right.”
Here’s the thing: it’s not your willpower. It’s not your discipline. It’s label math that’s designed to make products look better than they are and it trips up even people who’ve been at this for years. (Ask me how I know. Go ahead.)
I’m going to show you exactly how to do the math yourself, which ingredients are the worst offenders, and how to stop getting played by marketing departments. Let’s fix this.
The Basic Formula (It’s Not Complicated, I Promise)
Net carbs = the carbs your body actually absorbs and uses for energy. That’s it.
Net Carbs = Total Carbohydrates − Fiber − Sugar Alcohols
Fiber passes through you without being absorbed, so it doesn’t mess with your blood sugar or kick you out of ketosis. Full subtraction. Easy.
Sugar alcohols? That’s where things get spicy and where manufacturers get creative with their math.
Quick example: A medium avocado has 17.1g total carbs. Subtract 13.5g fiber. You’re at 3.6g net carbs. Done. Avocados are honest. Protein bars? Not so much.
Where the Labels Lie (This Is the Important Part)
Most tracking disasters happen right here, so stick with me.
Step 1: Figure out if you’re looking at a US or UK/EU label.
US labels make you do the math you subtract fiber from total carbs yourself. UK and EU labels already exclude fiber from the carbohydrate number, so if you subtract it again, you’re double counting and wondering why you’re “at 8 net carbs” but somehow starving.
Step 2: Deal with sugar alcohols and stop trusting the front of the package.
This is where manufacturers pull their favorite trick. They subtract 100% of all sugar alcohols from their net carb claims. But your body doesn’t process them all equally.
Subtract fully (100%):
- Erythritol basically invisible to your blood sugar
- Allulose same deal
- Monk fruit sweetener
Only subtract HALF (50%):
- Maltitol cheap, common in “keto” products, and absolutely not zero impact
- Glycerol shows up in a ton of protein bars
If the label just says “sugar alcohols” without telling you which kind, assume the worst and subtract only 50%.
Real math that’ll make you mad:
An Atkins bar that claims 3g net carbs with 11g maltitol in it:
23g total − 9g fiber − (11g maltitol × 0.5) = 8.5g net carbs
The label is off by 65%. SIXTY-FIVE PERCENT. And you’ve been wondering why you stalled.
Step 3: Don’t forget the serving size trap.
“1g net carbs per serving” across 20 servings means 20g if you finish the bag. (And let’s be honest, who eats one serving of anything?)
Also: foods under 0.5g carbs per serving can legally show “0g” on the label. Your “zero carb” coffee creamer, cooking spray, and sugar free gum? They add up when you use them four times a day. If you’re eating more than 3-4 “zero net carb” foods daily, track them anyway. The rounding lies accumulate.
Foods That Seem Fine But Will Absolutely Betray You
Nuts: A portion disaster waiting to happen
Pecans (1g/oz) and macadamias (~2g/oz) are chill. Almonds (3g/oz) need watching. Cashews at 7g/oz are basically carby imposters pretending to be keto friendly.
But here’s the real issue: nut butter. Almond butter at 4g per 2 tablespoons looks reasonable until you realize you just ate 4 tablespoons standing at the counter with a spoon. That’s 8g and you haven’t even had dinner yet. (Not that I’ve done this. Multiple times. This week.)
Cooked veggies: The sneaky concentration trick
Cooking removes water, not carbs. A cup of raw spinach is basically free. A cup of cooked spinach? That’s like 3-4 cups of raw spinach condensed down, and suddenly you’re at 6g.
Condiments: The silent budget killer
Ketchup runs 3-4g per tablespoon. BBQ sauce is 5-8g. That “small amount” of marinara is 3-4g per half cup. Two tablespoons of ketchup plus a quarter cup of marinara plus fresh vs jarred garlic = 10-15g you probably didn’t track.
Mustard, unsweetened hot sauce, and mayo are usually safe at 0-1g. Stick with those when you can.
The Six Mistakes That Stall Everyone
- Treating all sugar alcohols the same (maltitol is NOT erythritol, please remember this)
- Ignoring serving sizes and eating the whole bag
- Not adjusting for cooked vegetables
- Eating nuts straight from the container like a feral raccoon
- Trusting front of package claims without checking the actual math
- Forgetting condiments entirely
If you’ve stalled and you’re sure you’re doing everything right, try this: test your blood glucose before eating a suspect product, then again at 15 and 30 minutes. A jump over 10-15 mg/dL means that “keto friendly” product is hitting harder than advertised.
Or do a strict 7-day reset: weigh everything, track every condiment including carb count in garlic, verify every label. It’s tedious, but it almost always reveals the leak.
Your Homework (Just One Thing)
Tonight, grab one packaged “low carb” product from your kitchen. Do the math yourself using the steps above total carbs minus fiber minus properly adjusted sugar alcohols.
Now compare your number to what the label claims.
If your number is 2g or higher? You found your problem. And honestly, you probably found several of them.
This one habit actually verifying instead of trusting will do more for your progress than any hack, supplement, or willpower pep talk ever could.
Now go check that protein bar. I’ll wait.
