Note: This advice is given by the CAP Executive about non-broadcast advertising. It does not constitute legal advice. It does not bind CAP, CAP advisory panels or the Advertising Standards Authority.


As with all marcoms, testimonials should only be used if they are relevant, demonstrably genuine and do not mislead (slimtoneplus.com, 19 December 2012). We advise marketers to read the associated entries on “Weight control”.

The Weight Control section of the Code specifically refers to testimonials and states that testimonials that are not supported by trials do not constitute substantiation (Rule 13.1). Testimonials for weight-control products are acceptable if documentary evidence is held to prove they are genuine and if used only with the permission of the individual concerned (Rules 3.45 and 3.48). Marketers must however, hold scientific evidence that proves the general efficacy of their product (Lamphall Ltd, 11 December 2013, Miruji Health & Wellbeing, 2 May 2012, Pure Slim Ltd, 20 May 2009). Even if accurate, testimonials that individuals have lost exact amounts of weight should be compatible with good medical and nutritional practice (LiveLarge Ltd, 7 September 2011; PharmaPost, 7 May 2003; and Francois Leroy Slimming Centre, 21 August 2002).

Marketers should avoid including testimonials which either state or imply that one could potentially lose a precise amount of weight within a stated period of time (13.9). If proven, and in line with good nutritional practice, marketers are likely to be able to include testimonials which claim that certain individuals have lost exact amounts of weight in a given period (13.10). However, health claims that refer to a rate or amount of weight loss are not permitted in relation to food or food supplements (Rule 15.6.6).

Through the use of testimonials, marketers should not claim that a weight reduction regime can help with, or treat medical conditions. A complaint about an ad which stated, “I've cut my insulin from 40 units to 12 units and I am hoping to be insulin free by the end of next month” and “I used to suffer from regular tension headaches ... these have disappeared" was upheld because it implied that "The Harcombe Diet 30 Day Blitz" could treat medical conditions, and specifically diabetes and tension headaches. The ASA had seen no evidence to substantiate those claims and also considered that diabetes was a condition which required medical supervision, and therefore offers to treat it should only be made if that treatment would be supervised by a suitably qualified health professional (rule 12.1, 12.2, Zoë Harcombe, 3 December 2014)

The acceptable safe weight-loss limit, in line with Department of Health advice, is 2lbs a week (Naturland RB&M Research, 3 September 2003; H.B.R.I. Institute, 10 March 2004, and Equiba Institute, 28 August 2002). For example, the claim: “I lost 8lbs on the recommended diet plan!” is almost certainly unacceptable because the associated time period is unspecified. Similarly, a claim like “I lost 18 kilos in 4 weeks...I never dreamt that losing weight could be so easy. I thought I had tried just about every programme under the sun and then I ended up losing weight without lifting a finger...All I had to do was take some pills” is unacceptable because this is not compatible with good medical and nutritional practice, and implies the subject has lost weight without changes in food intake (PharmaPost, 7 May 2003).

Conversely, “I lost 8lbs in six weeks on the recommended diet plan!” is an acceptable claim, provided the general efficacy of the programme has been substantiated, the marketer holds signed and dated proof that the testimonial is genuine and has the subject’s permission to use it (3.48).

CAP and the ASA regard the use of before and after photos in the same way as testimonials. Marketers should therefore ensure that they meet the requirements of rules 3.45 to 3.48 of the CAP Code. They should hold signed and dated proof that the photos are genuine and have not been manipulated (EF Medispa, 20 February 2013, Windsor Group, 17 March 2004).

Marketers promoting a food (including soft drinks) or food supplements should take the Food Rules into account and note that weight loss and other claims of this nature, which directly result in an effect on one’s health, are considered to be health claims for the purposes of Section 15 of the Code. A health claim for a food should not be made unless that claim is compatible with an authorised claim listed on the EU Register of nutrition and health claims. See Weight control: Food and Food Supplements.

Even if a marketer holds signed and dated proof to show that before and after photos are genuine, the visual claims implied by the photos may render them problematic if they are seen to go beyond the meaning of an authorised claim on the EU register (ketonepremium.com, 10 July 2013).

See Weight control: General, Weight control: Food and Food supplements, “Testimonials and endorsements”, “Before and after photos” and other entries on “Weight control” and “Food”

Updated 31/12/2014


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