Low-Carb Food Labeling: What FDA Rules Mean for Food Manufacturers

"Low-carb food labeling" sits in a regulatory gray zone that creates real legal risk for food manufacturers. Keto, paleo, and low-carbohydrate product categories generate billions in annual consumer sales — yet FDA has never established a regulatory definition for what "low-carb" means on a food label. That gap is not an oversight. It is the current state of federal food labeling law, unchanged since FDA's nutrient content claim (NCC) regulations were promulgated in the early 1990s.

Under 21 U.S.C. § 343(r)(1)(A) and (r)(2)(A)(i), a food bearing an unauthorized NCC is considered misbranded under the Federal Food, Drug, and Cosmetic Act. FDA's regulations in 21 C.F.R. Part 101 explicitly exclude total carbohydrates from the framework of authorized "low" claims — codified in 21 C.F.R. § 101.54(a). Regardless of a product's actual carbohydrate content, no food label may lawfully carry a "low-carb" claim. Manufacturers who place such language on product packaging face warning letters, product detention, and potential enforcement action.

For regulatory compliance officers and in-house counsel at food manufacturers, understanding the specific legal boundaries of carbohydrate claims is foundational to any FDA food labeling laws and requirements compliance program. This article covers the legal basis for why low-carb claims are impermissible, how to lawfully declare carbohydrate content on the Nutrition Facts panel, how keto and paleo dietary descriptors are treated, where FDA and USDA authority diverge, and what 2024–2026 regulatory developments mean for carbohydrate labeling programs. Every regulatory position cited here is grounded in specific CFR and USC provisions.

Why "Low-Carb" Claims Are Legally Impermissible Under FDA Rules

What Are Nutrient Content Claims (NCCs)?

A nutrient content claim is any statement in food labeling that — expressly or by implication — characterizes the level of a nutrient in a product. Under 21 C.F.R. Part 101, Subpart D, manufacturers may use only those NCCs that FDA has formally authorized through rulemaking. Authorization requires FDA to establish specific, measurable criteria tied to a food's Reference Amount Customarily Consumed (RACC) — the standardized serving size benchmark used for most NCC calculations.

Each category of NCC requires distinct FDA authorization: "free" claims, "low" claims, "reduced" or "less" claims, "light" claims, and "high" or "rich in" claims all operate under separate regulatory standards. Common examples of authorized "low" claims include "low calorie," "low fat," "low saturated fat," "low cholesterol," and "low sodium." Each of these claims has defined regulatory thresholds. Manufacturers may use them only when a product meets the specific per-RACC criteria established in 21 C.F.R. Part 101.

"Low-carb" has no equivalent regulatory definition. No FDA rulemaking has established what carbohydrate level qualifies as "low" for NCC purposes. Without that regulatory foundation, no "low-carb" NCC is legally permissible — regardless of how few grams of carbohydrates the product actually contains.

Which "Low" Claims Are Authorized — and Why Carbohydrates Are Excluded

FDA's NCC regulations establish "low" claims for a defined set of nutrients, each with exact thresholds per RACC. Total carbohydrates are not among them. A citizens' petition to define "low-carb" was filed with FDA during the low-carb diet surge of the early 2000s — a period during which FDA also issued warning letters to food companies for using "low-carb" and "only X carbs" label language. No final rule has ever been issued in response to that petition, and FDA's regulatory agenda has not included carbohydrate NCC rulemaking in the years since.

The comparison table in the following section shows the authorized "low" NCCs with their thresholds — and where carbohydrates appear (or rather, do not appear) in that framework.

The Legal Basis: 21 C.F.R. § 101.54(a) and 21 U.S.C. § 343(r)

The prohibition on carbohydrate NCCs operates at both the statutory and regulatory level.

At the regulatory level, 21 C.F.R. § 101.54(a) expressly excludes total carbohydrates from the DRV-based NCC framework. The regulation provides:

"[A] claim about the level of a nutrient in a food in relation to the Reference Daily Intake (RDI) established for that nutrient in §101.9(c)(8)(iv) or Daily Reference Value (DRV) established for that nutrient in §101.9(c)(9), (excluding total carbohydrates) may only be made on the label or in labeling of the food if…"

21 C.F.R. § 101.54(a) (emphasis added). Total carbohydrates carry a Daily Reference Value — currently 275 grams based on a 2,000-calorie diet, as established under 21 C.F.R. § 101.9(c)(9) — but are explicitly carved out of the NCC authorization framework. The DRV exists; the authorized claim does not.

At the statutory level, 21 U.S.C. § 343(r)(1)(A) and (r)(2)(A)(i) establish that a food bearing a nutrient level characterization claim not compliant with FDA's NCC regulations is considered misbranded under the FD&C Act. The legal consequences of misbranding include FDA warning letters, product seizure, injunctions, and recalls. FDA has a documented history of enforcing this provision against food companies using low-carb language — enforcement that began during the early 2000s low-carb diet era and reflects the legal standard that remains in place today.

How FDA Defines "Low" for Other Nutrients (But Not Carbs)

The following table shows all nutrients for which FDA has established an authorized "low" NCC threshold, alongside the regulatory provision. The carbohydrate row reflects the current gap in the regulatory framework — a nutrient required to be disclosed on every Nutrition Facts panel, yet excluded from authorized claim status:

For every nutrient above, FDA has established measurable criteria tied to the RACC that manufacturers can verify and apply. Total carbohydrates appear on every Nutrition Facts panel and carry a Daily Reference Value — but FDA has never translated that value into an authorized NCC threshold. The result is a structured regulatory gap: the nutrient is required to be disclosed on every label but may not be characterized as "low" on any label.

Net Carbs, Dietary Fiber, and Sugar Alcohols: What the Label Must Show

Total Carbohydrate Declaration Requirements (21 C.F.R. § 101.9)

While carbohydrate level claims are impermissible, carbohydrate content declarations are mandatory. Under 21 C.F.R. § 101.9(c)(6), total carbohydrates must appear on the Nutrition Facts panel in grams per serving. The following sub-listings are required or conditionally required under the current Nutrition Facts label rules:

• Dietary fiber (total): Mandatory declaration. Soluble and insoluble fiber may be declared voluntarily as additional sub-listings.
• Total sugars: Mandatory declaration as a sub-listing under total carbohydrates.
• Added sugars: Mandatory declaration, required under the 2016 Nutrition Facts label final rule, appearing as a sub-listing under total sugars.
• Sugar alcohols: Must be declared as a sub-listing if a claim is made about sugar alcohols, or if the food contains sugar alcohols and a claim is made about sugars or calories from sugar alcohols.

These declaration requirements give manufacturers a lawful path to communicate carbohydrate content accurately — through the Nutrition Facts panel itself, without relying on any NCC.

The "Net Carbs" Problem: Why This Calculation Is Not FDA-Recognized

"Net carbs" is a consumer-marketing concept, not an FDA-regulated term. Consumers typically calculate it as: total carbohydrates minus dietary fiber minus sugar alcohols, based on the premise that fiber and sugar alcohols are not fully metabolized as glucose. While this calculation has a metabolic basis, FDA has not adopted it as a regulatory standard, and "net carbs" does not appear in 21 C.F.R. Part 101 or any other FDA regulation.

Placing "net carbs: X" on a food label as a prominent claim creates legal risk on two distinct grounds. First, it implies a characterization of the carbohydrate level in the food — which is the territory governed by NCC regulations. If construed as an NCC, the claim is unauthorized. Second, it uses a calculation with no regulatory definition, potentially constituting a misleading statement if presented as a defined regulatory value.

Manufacturers may include factual quantitative statements about carbohydrate content per serving consistent with 21 C.F.R. § 101.13(i)(3). A statement such as "Contains 5g total carbohydrates per serving" included in labeling — distinct from a front-of-label claim — is distinguishable from an NCC, provided it is accurate, not misleading, and does not function as a level characterization. The placement, prominence, and context of any such statement should be reviewed by food labeling counsel before finalization.

For related guidance on quantity disclosures in food labeling, the net quantity of contents declaration framework provides additional regulatory context on how factual quantity statements interact with label requirements under FDA rules.

Dietary Fiber and Sugar Alcohol Declarations

Dietary fiber and sugar alcohols are relevant to carbohydrate labeling beyond the "net carbs" discussion, particularly for manufacturers of keto and low-carb products that rely heavily on fiber and alternative sweeteners.

FDA draws a distinction between fibers that have demonstrated beneficial physiological effects on human health and fibers that do not, following the agency's 2016 Nutrition Facts label rulemaking. Only those fibers meeting FDA's definition of "dietary fiber" under 21 C.F.R. § 101.9(c)(6)(i)(A) may be counted in the total dietary fiber declaration. Manufacturers adding isolated or synthetic fibers to their products should confirm that those fibers meet FDA's current dietary fiber definition before relying on them in Nutrition Facts panel calculations.

Sugar alcohols — including erythritol, xylitol, sorbitol, maltitol, and others — are partially metabolized carbohydrates. Under 21 C.F.R. § 101.9(c)(6)(iii), sugar alcohols must be declared when a claim is made about them, or when the food contains sugar alcohols and a claim is made about sugars or calories from sugar alcohols. Manufacturers of products with significant sugar alcohol content should review both the Nutrition Facts declaration requirements and how any carbohydrate-related marketing language on the label interacts with those declarations.

Keto, Paleo, and Low-Carb Diet Claims on Food Labels

Can You Label a Food "Keto-Friendly"?

"Keto" and "keto-friendly" are not FDA-defined NCCs. FDA has not issued guidance establishing what makes a food suitable for a ketogenic diet, and there is no authorized standard for keto claims under 21 C.F.R. Part 101, Subpart D.

Manufacturers may use "keto-friendly" as a dietary descriptor — in a similar manner to how "Paleo," "Whole30 Approved," or similar dietary pattern terms appear in the marketplace. The regulatory risk, however, depends on context and presentation. If "keto-friendly" is used in a way that implies the food is "low-carb" or that it meets specific carbohydrate threshold criteria, the claim may be construed as an unauthorized NCC under 21 U.S.C. § 343(r).

Third-party keto certifications — such as those offered by private certifying organizations — reflect the certifying body's criteria, not FDA-established standards. Holding a third-party keto certification does not protect a manufacturer from FDA's NCC regulations if keto-related label language functions as a nutrient level characterization. The presence of a certification seal does not provide a regulatory defense.

Paleo and Other Diet-Specific Labeling

The same regulatory framework applies to "Paleo," "Whole30," and other diet-specific descriptors. FDA has not defined any of these dietary pattern terms as NCCs. Manufacturers may use them as marketing identifiers — but may not use them in ways that imply specific nutrient levels unless the underlying NCC requirements are independently satisfied.

The more prominent the claim and the more specific the implied nutrient content, the greater the regulatory risk. A "Paleo Certified" seal from a private organization carries different risk than a front-of-package statement like "Paleo-friendly — only 4g carbs," where the pairing of the dietary descriptor with a carbohydrate count could indicate a level characterization.

What Manufacturers Can and Cannot Say

The practical compliance boundary for low-carb product labeling comes down to a clear distinction between authorized disclosures and unauthorized claims:

Manufacturers should have food labeling counsel review all carbohydrate-related label copy before market launch or label refresh. FDA's warning letter database is publicly available and documents the agency's enforcement approach to these claims over time.

FDA vs. USDA: Which Agency Regulates Your Product's Label?

FDA-Regulated Packaged Foods

FDA regulates labeling for most packaged foods under the Federal Food, Drug, and Cosmetic Act and the Fair Packaging and Labeling Act. FDA's NCC regulations — including the prohibition on "low-carb" claims at 21 C.F.R. Part 101 — apply to FDA-regulated products. This covers the substantial majority of processed and packaged consumer food products: protein bars and shakes, beverages, snack foods, baked goods, dairy products, condiments, grain-based products, and most items sold through retail grocery channels.

If your product is not a meat, poultry, or egg product regulated by USDA's Food Safety and Inspection Service (FSIS), FDA's food labeling rules govern, and 21 C.F.R. Part 101 applies in full.

USDA/FSIS-Regulated Meat, Poultry, and Egg Products

USDA's Food Safety and Inspection Service regulates labeling for meat, poultry, and egg products under the Federal Meat Inspection Act and the Poultry Products Inspection Act. FSIS labeling requirements are codified at 9 C.F.R. Parts 317 and 381. FSIS operates a label approval process that differs significantly from FDA's self-certification system — many meat and poultry product labels require prior FSIS approval through the Label Submission and Approval System (LSAS) before the product may enter commerce.

The NCC framework in 21 C.F.R. Part 101 does not automatically apply to FSIS-regulated products. FSIS has its own NCC standards and prior-approval requirements for nutrient content claims on meat and poultry labels. Manufacturers producing keto-oriented meat or poultry products — keto snack sticks, low-carb beef jerky, protein packs containing poultry — must direct their labeling through FSIS, not FDA.

The Most Common Labeling Jurisdiction Mistake

The most frequent jurisdictional error in food labeling compliance is applying FDA's 21 C.F.R. Part 101 framework to products that require FSIS review, or submitting to FSIS review a product that falls under FDA's self-certification system. The determination of which agency governs a product is not always apparent from the ingredient list alone.

Products containing meat or poultry as an ingredient may fall under FSIS jurisdiction based on percentage-of-content thresholds. Combination products with both meat and non-meat components require case-by-case analysis — the agency with jurisdiction depends on the specific product formulation, the nature and percentage of regulated ingredients, and how the product is defined under the relevant statute. This analysis is among the most common issues OFW's food labeling attorneys resolve for food manufacturer clients.

Before finalizing label copy for any product containing meat, poultry, or egg ingredients, manufacturers should confirm jurisdictional authority and the applicable approval pathway. Our USDA labeling requirements guide covers the FSIS labeling process in detail and helps manufacturers determine which regulatory pathway applies to their product.

2024–2026 FDA Updates That Impact Low-Carb Labeling

The Updated "Healthy" Definition (Final Rule, December 2024)

On December 19, 2024, FDA published a final rule updating the regulatory criteria for the "healthy" NCC — the first significant revision to this claim definition since the regulations were first promulgated in the early 1990s. The rule became effective April 28, 2025, with a compliance deadline of February 25, 2028.

Under the updated criteria, a food may bear a "healthy" claim if it contains a meaningful amount from at least one of the recommended food groups or subgroups (fruits, vegetables, grains, dairy, protein foods) and meets specific per-serving limits for added sugars, saturated fat, and sodium. The update expanded eligibility for foods such as avocados, nuts, seeds, salmon, and olive oil — previously disqualified due to total fat content — and may exclude some sweetened yogurts and cereals that qualified under the prior standards.

The implication for low-carb labeling programs is significant for compliance analysis purposes: FDA has now demonstrated — with a published final rule — that it is willing and able to revisit NCC definitions that have been static since the early 1990s. The "healthy" final rule is direct evidence of that regulatory capacity. Yet carbohydrate claims — absent from the NCC framework for the same 30-plus year period — were not addressed in this rulemaking. The regulatory gap for "low-carb" claims persists, by FDA's affirmative omission.

Food manufacturers currently using "healthy" claims on product labels should review existing label copy against the new criteria. The February 25, 2028 compliance deadline provides a window, but label revision projects require lead time for reformulation analysis, label design, and legal review.

Front-of-Package Nutrition Labeling (Proposed Rule, January 2025)

On January 14, 2025, FDA proposed a mandatory front-of-package (FOP) nutrition label — a "Nutrition Info Box" that would appear on the front panel of most packaged foods. The proposed box would display saturated fat, sodium, and added sugars as "Low," "Med," or "High" based on the following Daily Value thresholds:

• Low: ≤ 5% Daily Value
• Medium: 6–19% Daily Value
• High: ≥ 20% Daily Value

The comment period for this proposed rule closed on July 15, 2025. A final rule is projected for Spring 2026.

The proposed FOP label does not include a carbohydrate indicator. Total carbohydrates — the nutrient directly relevant to low-carb product marketing — are not included in the mandatory FOP display. This absence, at the most visible point of product labeling, reinforces the regulatory gap that has existed in 21 C.F.R. Part 101 for decades. Manufacturers should monitor the Spring 2026 final rule, but should not anticipate any carbohydrate claim authorization arising from this rulemaking.

MAHA Diet Policy and the Future of Carbohydrate Claims

HHS Secretary Robert F. Kennedy Jr.'s "Make America Healthy Again" (MAHA) initiative has introduced political momentum for food labeling transparency that the regulatory environment has not seen in years. The Gluten Labeling Transparency Initiative, launched on January 21, 2026, reflects the administration's interest in expanding ingredient and nutrient disclosure requirements beyond current FDA standards.

The broader MAHA food policy direction — which emphasizes diet-related disease reduction and ingredient transparency — is directionally consistent with the kind of regulatory reform that could, over time, include carbohydrate content claims. The administration has expressed concern about ultra-processed foods and diet-related chronic disease, areas where carbohydrate quality and quantity are part of the public health discussion.

Political will and regulatory action, however, are different processes. A final rule establishing "low-carb" as an authorized NCC would require a full rulemaking proceeding: scientific substantiation supporting a specific carbohydrate threshold, a proposed rule with public comment, and a final rule publication. That process is measured in years, not months, and depends on FDA's regulatory priorities and available resources. As of March 2026, no specific rulemaking for carbohydrate NCCs has been included in FDA's regulatory agenda, and no proposed rule has been issued.

Manufacturers should not treat current MAHA policy statements as authorization to use carbohydrate claims that remain legally impermissible under existing NCC regulations.

What This Means for Food Manufacturers Right Now

The 2024–2026 regulatory developments produce four concrete compliance implications:

• Review "healthy" claims immediately: The updated NCC criteria became effective April 28, 2025. If any existing product labels bear "healthy" claims, those claims must be reviewed against the new food group and nutrient limit criteria. The February 25, 2028 compliance deadline is the outer limit — manufacturers should begin label review and reformulation analysis now.
• Monitor the FOP final rule: Expected Spring 2026, this rule will require front-of-package Nutrition Info Box implementation on most packaged foods. Compliance timelines will follow publication of the final rule.
• Do not assume MAHA signals change current NCC law: The carbohydrate NCC prohibition in 21 C.F.R. § 101.54(a) is unchanged. MAHA policy direction does not modify the regulatory text.
• Consider the petition process if the business case exists: Manufacturers with genuine interest in establishing an authorized low-carb NCC standard should explore the citizen petition process under 21 C.F.R. § 101.69. The current political environment may be more receptive than prior eras, but the petition itself must include thorough scientific substantiation.

Compliance Steps for Food Manufacturers

What You Can Say About Carbohydrates on Your Label

Manufacturers have three lawful pathways for communicating carbohydrate content to consumers without triggering NCC restrictions:

Nutrition Facts panel declarations are the primary vehicle. Under 21 C.F.R. § 101.9(c)(6), total carbohydrates, dietary fiber, total sugars, and added sugars must appear on the Nutrition Facts panel. This declaration communicates actual carbohydrate content per serving without requiring any NCC.

Factual quantitative statements about carbohydrate content per serving — such as "Contains 5g total carbohydrates per serving" in label copy — may be permissible when truthful, accurate, and not presented in a way that functions as a level characterization. Consistency with 21 C.F.R. § 101.13(i)(3) and context review by food labeling counsel is important before any such statement is finalized.

Substantiated structure/function claims that describe a physiological benefit — such as "supports ketone production when incorporated into a ketogenic diet" — may be permissible if the claim is truthful, not misleading, and properly substantiated. Structure/function claims operate under a different regulatory framework than NCCs and require their own compliance review.

What Will Get You a Warning Letter

Based on FDA's historical enforcement record and the NCC regulations in 21 C.F.R. Part 101, the following categories of label language present misbranding risk:

FDA's warning letter database is publicly accessible at FDA.gov. Reviewing recent food labeling warning letters before finalizing any carbohydrate-related label copy is a standard step in a labeling compliance review.

How to Petition FDA for a New Nutrient Content Claim (21 C.F.R. § 101.69)

The process for establishing a new authorized NCC — including a regulatory definition for "low-carb" — is a citizen petition filed under 21 C.F.R. § 101.69. A complete petition must include a proposed definition with specific threshold criteria, scientific substantiation demonstrating that the claim is nutritionally meaningful and would not mislead consumers, analysis of how the proposed claim would interact with existing NCC regulations, and proposed regulatory text for the new rule.

FDA's response timeline for NCC petitions is measured in years, not months. The early 2000s petition to define "low-carb" — filed during the height of the Atkins diet era and backed by significant industry and consumer interest — received no final FDA action. Petitions gain traction when they include thorough scientific support, quantitative threshold proposals grounded in clinical and epidemiological evidence, and broad stakeholder backing from food industry associations and public health organizations. A food labeling attorney with FDA petition experience can assess the viability of a petition and help build the required administrative record.

OFW Law's Food Labeling Compliance Practice

OFW Law represents food manufacturers, importers, and exporters on FDA and USDA food labeling matters. Our regulatory practice works with compliance officers and in-house legal teams on label review, NCC compliance programs, pre-market label approvals, and regulatory response when FDA or FSIS raises labeling concerns. We bring agency insight to labeling questions that do not have simple answers — including the carbohydrate claim questions that this article addresses.

One of the primary services our food labeling practice provides is jurisdictional analysis — determining whether a product's label falls under FDA or USDA/FSIS authority and which regulatory pathway applies. For manufacturers producing keto, paleo, or low-carb products that contain meat, poultry, or egg components, that analysis is the starting point for any label development process.

If your organization is reviewing existing labels for NCC compliance, building a carbohydrate labeling strategy for new product launches, or evaluating a citizen petition for a new nutrient content claim, contact OFW Law for a consultation with our food labeling attorneys at ofwlaw.com/contact.

Frequently Asked Questions