National Advertising Review Board Upholds Qualified Clinically Proven Claim for SlimFast Plan; Recommends “Clinically Proven” Product Claims Be Discontinued

For Immediate Release
Contact: Abby Hills, Director of Communications, BBB National Programs

703-247-9330 /

New York, NY – January 5, 2022 – A panel of the National Advertising Review Board (NARB), the appellate advertising law body of BBB National Programs, has concluded that KSF Acquisition Corp. (SlimFast) has proper substantiation for a qualified claim that the SlimFast Plan is clinically proven but found that SlimFast’s product-related “clinically proven” claims are unsubstantiated. To ensure that consumers are not confused or misled by claims relating to its SlimFast Plan, the NARB panel has recommended that SlimFast: 

  • Discontinue unqualified clinically proven claims for its SlimFast food products, including “Clinically Proven: Lose Weight and Keep it Off”
  • Modify the “clinically proven” claim, on product packaging or otherwise, to make clear that it is the “SlimFast Plan”, and not any individual product, that is clinically proven to help users “Lose Weight and Keep It Off”; and
  • Modify any claim by SlimFast that its controlled, low-calorie, meal replacement SlimFast Plan is “clinically proven” by including in the body of the claim a statement explaining the three components of the Plan: Per day, one sensible meal, two meals replaced with shakes, smoothies or bars, and three snacks between meals to satisfy hunger.


The NARB panel declined to adopt the recommendation of the National Advertising Division (NAD) that the advertiser qualify its “lose weight and keep it off” claim to disclose that long-term weight maintenance will likely include some weight regain. 

The advertising at issue had been challenged by Simply Good Foods (Atkins) before NAD. Following NAD’s decision (Case No. 6952), SlimFast appealed certain NAD findings and recommendations.

The claim “Clinically Proven: Lose Weight and Keep It Off” appears prominently on the facing panel of each of SlimFast’s more than forty products (shakes, snacks, and bars). The NARB panel found that one of the messages reasonably communicated by this package claim is that individual SlimFast food products have been clinically proven to result in weight loss. Because individual products have not been clinically evaluated the NARB panel found that clinically-proven claims relating to individual products are unsubstantiated and, therefore, recommended that those claims be discontinued.

In evaluating SlimFast’s “clinically proven” claim as applied to the SlimFast “Plan” (a low-calorie meal replacement-based plan accounting for approximately 1,200 calories per day), the NARB panel considered that the Plan, as presented by SlimFast, consists of, per day, one sensible 500-calorie meal, two meals replaced with shakes, smoothies, or bars, and three low-calorie snacks between meals. Departing from NAD’s recommendation, the NARB panel concluded that SlimFast has proper substantiation for its claim that the SlimFast Plan has been clinically proven. However, to ensure that consumers are not confused or misled, the panel recommended that any use in advertising of the clinically proven claim should include, in the body of the claim, an express reference to the SlimFast Plan as well as an explanation of the three components of the Plan.

Regarding the “keep it off” portion of the “lose weight and keep it off” claim, the evidence in the underlying record indicated that as much as 22% of the weight lost after six months was regained after another six months. The NARB panel concluded that this 22% reduction in weight loss falls within the scope of a reasonable interpretation of the claim “lose weight and keep it off.” Therefore, the panel declined to recommend that the claim include a disclosure that long-term weight maintenance will likely include some weight regain.

SlimFast stated that it “agrees to comply with the NARB’s decision and more prominently connect the ‘clinically proven’ claim to the SlimFast Plan.” The advertiser further stated that although it “respectfully disagrees with the NARB’s opinion that the ‘clinically proven’ claim on the facing panel of product packaging is not properly qualified” it “believes in transparent advertising and agrees to implement changes to more prominently reference the elements of the SlimFast Plan in connection with the ‘clinically proven’ claim on product packaging.”

All BBB National Programs case decision summaries can be found in the case decision library. For the full text of NAD, NARB, and CARU decisions, subscribe to the online archive.


About BBB National Programs: BBB National Programs is where businesses turn to enhance consumer trust and consumers are heard. The non-profit organization creates a fairer playing field for businesses and a better experience for consumers through the development and delivery of effective third-party accountability and dispute resolution programs. Embracing its role as an independent organization since the restructuring of the Council of Better Business Bureaus in June 2019, BBB National Programs today oversees more than a dozen leading national industry self-regulation programs, and continues to evolve its work and grow its impact by providing business guidance and fostering best practices in arenas such as advertising, child-directed marketing, and privacy. To learn more, visit

About the National Advertising Review Board (NARB): The National Advertising Review Board (NARB) is the appellate body for BBB National Programs’ advertising self-regulatory programs. NARB’s panel members include 85 distinguished volunteer professionals from the national advertising industry, agencies, and public members, such as academics and former members of the public sector. NARB serves as a layer of independent industry peer review that helps engender trust and compliance in NAD, CARU, and DSSRC matters. 

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