Guide
"Net carbs" has no official FDA definition
Every keto dessert label subtracts something to arrive at a lower "net carbs" number. The FDA has never defined what that subtraction should be — which means two products with identical ingredients can legally print two different "net carb" counts.
Database v0.0.1 (draft) — updated 2026-07-21
In the repair
What does the FDA actually regulate on a Nutrition Facts label?
The FDA defines and requires four carbohydrate-related lines: "Total Carbohydrate," "Dietary Fiber," "Total Sugars," and "Added Sugars." "Net carbs" is not one of them — it does not appear anywhere in FDA nutrition-labeling regulation as a defined, calculated, or required term.
Source: FDA Nutrition Facts label regulatory framework (Total Carbohydrate/Fiber/Sugars/Added Sugars lines); cross-referenced against the allulose labeling guidance discussed on the allulose page, which shows the FDA's specific, narrow labeling carve-outs by contrast.Where did "net carbs" come from, then?
It's an informal, industry-popularized convention that grew out of low-carb diet marketing (originally associated with products like Atkins-branded foods), not a regulatory requirement. The common formula subtracts dietary fiber and some or all sugar alcohols from Total Carbohydrate — but "some or all" is exactly the problem: there's no single agreed rule for how much of a given sugar alcohol to subtract.
Source: general nutrition-labeling literature and industry practice discussion (no single FDA rule exists to cite, which is itself the point of this page).Why does that matter for sweeteners like allulose or maltitol?
Different sugar alcohols and rare sugars have different real absorption rates — erythritol is ~90% excreted unchanged (near-zero net effect), while maltitol has a distinctly non-zero glycemic response in both its powder and syrup forms (see the maltitol page). A brand that subtracts 100% of any sugar alcohol from its "net carbs," regardless of which one it is, can understate the real carbohydrate impact of a dessert containing a less-inert sweetener like maltitol.
Source: Database v0.1 sweetener entries — see erythritol and maltitol pages for the specific per-sweetener absorption/GI data.What does RecipeMend show instead of "net carbs"?
RecipeMend's repair tool shows each ingredient's actual carbs and sugars per 100g from Database v0.1, plus its glycemic-index bucket, rather than computing an unregulated "net carb" subtraction. Where the underlying number is itself uncertain (see the maltitol and molasses entries in Sources), that's flagged with a confidence level instead of folded into one clean-looking net number.
Source: Database v0.1, this repair tool's methodology — see How it works.How to count carbs for a dessert, the honest way
If "net carbs" isn't regulated, what should you actually do? Three rules — each tied to a number RecipeMend can cite from Database v0.1, not a marketing formula.
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1. Start from Total Carbohydrate — the one line the FDA actually defines.
"Total Carbohydrate" is a required, regulated Nutrition Facts line; "net carbs" is not. Begin every dessert estimate from Total Carbohydrate (or, for a bare ingredient, its carbs-per-100g), then decide — deliberately — what, if anything, to subtract. Starting from a brand's pre-computed "net carbs" hides the subtraction you never got to check.
Source: FDA Nutrition Facts regulated carbohydrate lines (Total Carbohydrate / Dietary Fiber / Total Sugars / Added Sugars). -
2. Subtract only what the evidence supports — and treat the three "subtractable" categories differently.
Not everything people subtract behaves the same way in the body:
- Dietary fiber — the least controversial subtraction; it's largely unabsorbed, and it's a defined FDA label line, so removing it from Total Carbohydrate is the one step with broad backing.
- Sugar alcohols vary enormously. Erythritol is roughly 90% absorbed and excreted unchanged with a glycemic index near 0 — close to fully subtractable. Maltitol is not: Database v0.1 records a GI of about 29–36 for the powder and about 52 for the syrup, both distinctly non-zero. Subtracting 100% of maltitol the way you might erythritol understates the real carb impact.
- Allulose is a rare sugar the FDA lets manufacturers leave off the "Total Sugars" and "Added Sugars" lines (2020 guidance), yet it still counts toward Total Carbohydrate and its measured glycemic response is low (GI ~0 in Database v0.1). So a label can legally show low "sugars" while the carbohydrate is still on the Total Carbohydrate line.
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3. Work it through on the real ingredient list — here's a worked example.
Take three sweetening ingredients straight from Database v0.1, per 100g:
- Granulated white sugar — ~100g carbs / 100g, essentially all sugar (GI ~65, bucketed high-spike). Nothing to subtract: the full carbohydrate is glucose-relevant.
- Erythritol — labeled ~100g carbohydrate / 100g, but GI ~0 and ~90% excreted unchanged, so its glycemic contribution is close to nil. This is the case where subtraction is genuinely defensible.
- Maltitol (powder) — ~100g carbohydrate / 100g with GI ~29–36. Real, partial impact — subtract some, but not all, and know the exact fraction isn't settled (Database v0.1 keeps this at low confidence).
Swap the cup of white sugar in a recipe for erythritol and the honest read is "roughly the same labeled carbohydrate, but a near-zero glycemic contribution." Swap it for maltitol and the honest read is "lower than sugar, but not zero — count a real, if uncertain, share." The point isn't one clean subtracted number; it's knowing which of your ingredients actually earns the subtraction.
Source: Database v0.1 ingredient/sweetener entries — white sugar (USDA FDC 169655, ~100g carbs/100g, GI ~65), erythritol (GI ~0), maltitol powder (GI ~29–36, low confidence).
Don't want to do this by hand? Paste a recipe and RecipeMend shows each ingredient's cited carbs, sugars, and glycemic bucket — the honest per-ingredient breakdown, not one invented net number.
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Paste your recipe and get sourced carbs/sugars per ingredient, not an unregulated net-carb subtraction.
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