Weight Loss If-Then Statements and The FTC

Introduction
"With Enforma, you can eat what you want and never, ever, ever have to diet again." is the claim made by Enforma as documented on the FTC site describing this case. Paraphrasing this, "If you take Enforma, Then you can eat what you want without having to diet."

How Could They Justify The Validity of Their Claim?
To provide evidence for their claim, the company needed to have the product tested extensively by an indepenent unbiased party.  Some test subjects would be given the product and some would be given a placebo. If the group taking the product kept off fat substantially better in X percent of the group taking the product as compared to the the control (placebo) group, then a claim that "Enforma was found to keep fat off in X percent of test subjects as compared to a control group" could be made.

The infomercials advertising this product provided testimonials, but these testimonials were not sufficient proof of the products claims.  The FTC stated:  Defendants did not possess and rely upon a reasonable basis that substantiated the representations set forth in Paragraph 15 above, at the time the representations were made.

Why Don't Testimonials Serve As Solid Evidence?
Product testimonials, in general, are experiences provided by consumers in uncontrolled environments. For example, people could experience success with a weight loss product because they also dieted and exercised while using the product.  In addition, negative testimonials are usually not included.

How Do We Disprove or Prove a Claim?
To disprove If I USE PRODUCT A AS DIRECTED, Then RESULT B OCCURS we must show that RESULT B does not occur when PRODUCT A is USED AS DIRECTED.

To prove If I USE PRODUCT A AS DIRECTED, Then RESULT B OCCURS is true we must show that RESULT B always occurs when PRODUCT A is USED AS DIRECTED.

Proving a claim is difficult and requires well-structured testing.  Generally, companies will usually add such disclaimers as "Results Will Vary".  This type of added language waters down the claim greatly. For more on writing a guarantee that never has to be honored, see this page.