Weighing up how to make diet and detox claims in your ad? Don’t bite off more than you can chew, read our top tips on getting your ad right.

This advice is distinct from that for food or food supplements, which claim to aid weight loss, the advertising of which will invoke the food rules.

Does the evidence add up?

1. A calorie-controlled diet is accepted as an effective means of losing weight (13.1) and marketers will be expected to hold evidence that their diet works in this way;

2. Unproven claims for “fad” diets which do not follow the UK Government’s nutritional guidelines, such as the Atkins Diet, should be avoided.

Steer clear of exaggeration

3. As much as we would all love to find a diet that allows us to eat as much as we like and still lose weight, rule 13.8 of the Code prohibits such claims. Ads should also not suggest that weight loss will be permanent;

4. Marketers shouldn’t claim that people can lose precise amounts of weight within a stated period (see the Zoe Harcombe ruling) or that weight or fat can be lost from specific parts of the body (13.9).

Make sure the ad is responsible

5. Think about who the ad is targeting. Marketers must be able to show that their diet plans are nutritionally well-balanced for the target audience (13.5);

6. Diet ads shouldn’t appeal particularly to under 18s or those for whom the diet could produce a potentially harmful body weight, in other words a BMI of less than 18.5.

7. Equally, care should be taken when advertising diets to obese people.

8. According to rule 13.3, ads for diets shouldn’t state or imply that being underweight is desirable or acceptable. The ASA would likely take a dim view of an ad which could encourage vulnerable people to engage in competitive dieting or unhealthy eating habits (see the Michael Joseph ruling).

Testimonials and Before & After pics

9. Featuring “successful dieter” , like in LighterLife UK Ltd, is one method marketers might deploy to demonstrate the effectiveness of the diet. If the ad states exactly how much weight the dieters have lost, it also needs to state the timeframe in which they lost it. The rate of weight loss quoted needs to be compatible with good medical and nutritional practice (13.10). If before and after pictures or testimonials are used, they should be realistic and not exaggerate the amount of weight loss.


10. In a nutshell, detox claims are likely to lead to problems. Cutting out alcohol and fatty foods could lead to weight loss (see point 1) but the ASA hasn’t yet seen evidence to support the efficacy of detox wraps, patches, devices or supplements.

By Victoria Bugler, Compliance Executive


Victoria studied European Business Studies and French at the University of Ulster and completed her Postgraduate in Law at the College of Law in Guildford. Victoria joined the ASA in 2005 as an Investigations Executive and moved to the Compliance team in 2009. The Compliance team ensure that ASA decisions are adhered to using a variety of approaches including swiftly acting to remedy non-compliant ads, co-ordinating sanctions, undertaking media and issue-specific project work and effectively monitoring of ads across all media.

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