Keto bars: differences in sugar alcohol and fiber labeling practices

I didn’t plan to go down a labeling rabbit hole, but one afternoon in the snack aisle I realized three “keto” bars—same size, same vibe—promised wildly different “net carbs.” I stood there comparing fiber grams, sugar alcohol types, and serving sizes, thinking: am I reading three dialects of the same language? That moment pushed me to sit down and unpack why labels on keto bars vary so much, especially around sugar alcohols and dietary fiber. What follows is my best attempt to translate the fine print into plain English, along with what I now check before a bar ever reaches my cart.

Why two keto bars can disagree on the same shelf

Here’s the tension I kept bumping into: the Nutrition Facts label follows legal definitions and specific calculation rules, but marketing claims (like “net carbs”) sit outside the official panel. There’s room for different house rules. One brand subtracts all sugar alcohols and fiber from total carbs, another subtracts only certain sugar alcohols, and a third adds asterisks and footnotes. Meanwhile, FDA rules treat sugar alcohols differently from sugars and set strict criteria for what may count as “dietary fiber” on the panel (see FDA’s Q&A and label resources here and here). That alone explains a lot of the mismatch.

• Big idea: “Net carbs” is a marketing calculation, not a regulated line on the Nutrition Facts panel. Expect variation.
• FDA allows manufacturers to voluntarily list grams of “sugar alcohol” under Total Carbohydrate; it is not required for every product (see FDA’s interactive label explainer here).
• What qualifies as “dietary fiber” is defined; some added fibers count and some do not, based on demonstrated health effects. Labels reflect this.

The rulebook behind sugar alcohols on labels

Sugar alcohols (polyols) like erythritol, xylitol, and maltitol are not “sugars,” so they don’t show up as Added Sugars. They do, however, contribute to Total Carbohydrate. FDA gives specific calorie values for each polyol—erythritol is treated as 0 kcal/g, maltitol around 2.1 kcal/g, xylitol 2.4 kcal/g, and so on (see 21 CFR 101.9 here). That’s why two bars with the same grams of “sugar alcohol” can have different calorie counts. It also hints at why brands make different net-carb arguments: if a polyol contributes little or no calories and has a smaller glucose/insulin impact, some companies subtract most or all of it in their marketing math.

• Erythritol: labeled at 0 kcal/g in U.S. rules; often fully subtracted in “net carb” tallies.
• Maltitol: about 2.1 kcal/g by regulation; many consumers report GI sensitivity at moderate intakes, so more subtraction can be misleading for appetite or comfort.
• Hydrogenated starch hydrolysates (HSH): can be ~3.0 kcal/g; labeling and tolerance vary.

Key practical note: the “Sugar Alcohol” line is optional. One brand might list it, and another might leave it out even if polyols are present (you can still spot them in the ingredients). If “sugar alcohol” isn’t listed, you can’t assume zero—check the ingredient list for erythritol, maltitol, xylitol, sorbitol, isomalt, mannitol, or HSH. For a refresher, FDA’s consumer-facing label explains this briefly here.

Fiber on labels is not just “anything planty”

I used to assume any plant-derived powder labeled as fiber would count toward the fiber grams. FDA’s definition is tighter. Fibers may be “intrinsic and intact” (naturally occurring in foods like nuts, seeds, or chicory root) or added isolated/synthetic carbohydrates that FDA recognizes as beneficial to health (e.g., lowering blood glucose or cholesterol, increasing stool frequency). FDA maintains what amounts to an approved list and keeps guidance updated (see FDA’s Q&A here). If a particular added carbohydrate hasn’t been shown to provide a qualifying benefit, it shouldn’t be counted as “dietary fiber” on the panel.

• Why it matters: Two bars can use different “fiber” ingredients; one may count on-label, another may not, depending on the evidence and FDA’s determinations.
• Testing methods: Labs often rely on AOAC methods to quantify total, soluble, and insoluble fiber in complex foods; newer consensus methods aim to capture resistant starches and low-molecular-weight fractions (see a methods overview here).
• Calorie math: FDA uses general factors for non-digestible carbs (e.g., 2 kcal/g for certain soluble non-digestible carbohydrates), which affects total calories even when fiber grams look the same (see FDA rule preamble PDF here).

How “net carbs” became a choose-your-own-adventure

Because “net carbs” isn’t an FDA-defined term, brands can set different house rules. The most common formulas I’ve seen:

• Simple subtraction: Net carbs = Total Carbohydrate − Fiber − Sugar Alcohols.
• Selective subtraction: Subtract all fiber, but only some sugar alcohols (e.g., subtract erythritol fully, but only half of maltitol).
• Adjusted for serving size: Same math, but quietly changes the serving size from 1 bar to 1/2 bar in the fine print.

None of these is right or wrong in a moral sense; they reflect different assumptions about digestibility and glycemic impact. The problem is when a package splashes a big “2g net carbs” on the front and uses a tiny serving or generous subtractions to get there. FDA does regulate the Nutrition Facts label itself (including Added Sugars), but not the “net” number. If you want healthier consistency, default to the official panel and your own arithmetic, using the rules you trust most (with your clinician’s input if you manage diabetes or a medical condition). The FDA’s explainer on Added Sugars clarifies what must be counted on the panel here.

My three-step way to compare keto bars without getting lost

I started doing this checklist in the store, and it saved me from impulse buys that didn’t match my goals.

• Step 1 — Start with the panel: Look at Total Carbohydrate, then scan the indented lines (Dietary Fiber, Total Sugars, Added Sugars, and—if present—Sugar Alcohol). Note the serving size and whether “1 bar” equals a full bar.
• Step 2 — Read the ingredient list: Identify which polyol is used (erythritol vs. maltitol matters for calories and tolerance) and which fiber sources appear (inulin/chicory root, soluble corn fiber, psyllium, cellulose, etc.). Cross-check whether those fibers are recognized by FDA to count on-label (FDA keeps an updated list in guidance and Q&A).
• Step 3 — Do your own net-carb math: If you track net carbs, pick a consistent formula. I personally subtract all listed dietary fiber. For polyols, I subtract all erythritol but am more conservative with maltitol/HSH. Your body’s response and tolerance matter more than the front-of-pack slogan.

Small details that change the numbers in surprising ways

Once you start looking closely, label math gets interesting:

• Calorie factors differ by polyol: Erythritol (0 kcal/g) is treated differently from maltitol (~2.1 kcal/g) and HSH (~3 kcal/g) in U.S. regulations (21 CFR 101.9 lists the factors). Two bars can have equal grams of “sugar alcohol” but different calorie totals because the kinds differ.
• Fiber can be partially soluble or insoluble: Only certain added fibers count toward “Dietary Fiber.” If a bar uses a novel fiber not recognized as beneficial (yet), those grams may not legally appear as “fiber” on the panel even if marketing copy mentions “prebiotic.”
• Voluntary listing of sugar alcohols: A brand might include “Sugar Alcohol 12 g,” while another lists none but still uses erythritol high in the ingredients. The absence of a line doesn’t prove absence of polyols—check ingredients.
• Serving tricks: A “low net carb” claim sometimes hinges on a fractional serving or on rounding rules. Scan for asterisks and confirm the serving equals the unit you plan to eat.

What I now look for on keto bar labels

Shopping without second-guessing feels good, so I keep these filters in mind:

• Fiber quality first: Ingredients like inulin/chicory root, psyllium husk, pectin, or cellulose are common; I glance at the order (higher = more) and assume anywhere from 0–2 kcal/g for non-digestible carbs per FDA’s energy factors. I avoid bars where “fiber” is vague and unsupported.
• Erythritol vs. maltitol: If I see erythritol, I expect lower calories per gram and usually better tolerance; with maltitol or HSH, I anticipate more calories and a higher chance of GI rumbling for me.
• Added sugars separate from polyols: The Added Sugars line should be low (ideally 0 g) if a bar markets itself as “keto.” Polyols are not “Added Sugars,” so check both lines, not just one.
• Transparent math: If a package prints a net-carb number, I check whether it matches a consistent formula I’m comfortable with. If it doesn’t, I defer to the official panel and recalculate.

Digestive comfort matters more than the math

Keto bars can be convenient, but your gut isn’t a spreadsheet. Many people find they tolerate erythritol-based products better than maltitol-heavy ones. Sorbitol and mannitol tend to be more gas-producing for some. Labels give clues but can’t predict your exact response. I keep a simple note on my phone where I jot the bar name, the polyol used, the fiber source, and how I felt after eating it. Patterns show up fast.

When the science and the label talk to each other

Behind the scenes, labs use standardized methods to calculate fiber fractions in complex products; consensus methods like AOAC’s help keep numbers from drifting across brands. FDA periodically updates guidance so the Nutrition Facts panel evolves with evidence. A helpful way to think about it: the label is a living translation of current science into consumer numbers (see AOAC methods overview here and FDA dietary fiber Q&A here).

My pocket guide for the grocery aisle

• Scan the panel: Total Carbohydrate → Dietary Fiber → Added Sugars → Sugar Alcohol (if listed).
• Match the ingredients: Identify the specific polyol(s) and fiber(s).
• Recalculate net carbs your way: Use one consistent rule each time so you can compare across brands.
• Check serving size: Make sure “1 serving” equals what you’ll actually eat.
• Listen to your body: Keep brief notes on tolerance and appetite; adjust choices accordingly.

Signals that tell me to slow down and double-check

• Too good to be true net carbs: Front-of-pack claims that don’t reconcile with the official panel or ingredient list. I recalc.
• Vague fiber names: “Plant fiber blend” without specifics raises questions about what actually counts on-label.
• GI warnings: If sorbitol, mannitol, or large amounts of maltitol show up early in ingredients, I start cautiously and see how I feel.
• Hidden serving size games: If the serving is half a bar, I double the numbers I care about.

When uncertainty lingers, I go back to official explainers: FDA’s Added Sugars page is concise here, and the sugar alcohol explainer is a quick refresher here. For calorie factors and the fine print, the Code of Federal Regulations is the anchor here.

What I’m keeping and what I’m letting go

I’m keeping a calm, label-first approach and a short list of bar brands that use fibers I know I tolerate. I’m letting go of the idea that every “keto” front claim maps neatly to the Nutrition Facts panel—there’s too much accepted variability. The principles I bookmark:

• Use the panel, not the pitch: Total Carbs and Dietary Fiber are standardized; “net carbs” is not.
• Polyol specifics matter: Erythritol is treated as 0 kcal/g; maltitol and HSH are not. Expect different calorie impact.
• Fiber is defined, not assumed: Only recognized fibers count on-label; look them up if you’re unsure.

If you want to go deeper or verify a confusing label, start with FDA’s consumer pages and—when needed—the CFR. They’re not flashy reads, but they’re the foundation I wish I had started with.

FAQ

1) Are sugar alcohols counted as “Added Sugars” on the label?
Answer: No. Sugar alcohols are not “sugars,” so they are not listed as Added Sugars. They may be listed voluntarily as “Sugar Alcohol” under Total Carbohydrate. See FDA’s label explainer for a quick overview.

2) Why do some bars subtract all erythritol but only part of maltitol?
Answer: Different brands use different assumptions. U.S. rules treat erythritol as 0 kcal/g, while maltitol has about 2.1 kcal/g. Companies sometimes reflect that in their “net carb” math, which is a marketing calculation rather than a regulated line.

3) Do all added fibers count toward the “Dietary Fiber” grams?
Answer: Not automatically. FDA recognizes certain intrinsic fibers and a list of added fibers with demonstrated health benefits. Others may not count on the label until evidence supports them.

4) Why does the same amount of “sugar alcohol” change the calorie total?
Answer: Different polyols have different calorie factors in U.S. regulations (e.g., erythritol 0, xylitol ~2.4, HSH ~3 kcal/g). The mix used in a bar shifts the final calorie number.

5) Is there a “correct” net carb formula?
Answer: There isn’t one official formula in U.S. labeling. Choose a consistent approach that aligns with your goals and tolerance, and rely on the Nutrition Facts panel for standardized numbers.

Sources & References

• 21 CFR 101.9 Nutrition labeling
• FDA Dietary Fiber Q&A (2024)
• FDA Nutrition Facts Label Resources
• FDA Sugar Alcohols Explainer
• AOAC Dietary Fiber Methods (2023)

This blog is a personal journal and for general information only. It is not a substitute for professional medical advice, diagnosis, or treatment, and it does not create a doctor–patient relationship. Always seek the advice of a licensed clinician for questions about your health. If you may be experiencing an emergency, call your local emergency number immediately (e.g., 911 [US], 119).