Weight and slimming

Helpful information on the advertising rules for weight-loss and slimming products and examples of previous Advertising Standards Authority rulings in this area.

Ads for weight-loss and slimming products are allowed to sell us a dream or aspiration, but advertisers need to make sure their claims have a firm foundation in reality. Most of the complaints we receive about weight-loss and slimming products are related to the capability of the product, and this capability being exaggerated in the ad.

The advertising rules state any claim made for the effectiveness of a weight-loss or slimming method or product should be backed by rigorous practical trials conducted on people. Testimonials that are not supported by trials do not constitute adequate evidence.

Claims that specify a precise amount of weight-loss within a specific time period should be avoided. As should claims that state a weight-loss or slimming product can help you lose weight from a specific part of the body.

As well as making sure their ads are honest and don’t mislead consumers, advertisers marketing weight-loss or slimming methods or products should ensure their ads do not exploit vulnerable groups and are prepared with a degree of social responsibility. Ads shouldn’t be targeted at, or appeal to, consumers under-the-age of 18 or those for whom weight reduction is likely to result in a potentially harmful body weight. Ads should never suggest that it is desirable to be underweight.

Furthermore, it is important for advertisers to remember the amount of weight-loss that can be achieved by an individual depends on many factors. It is not the same for everyone and it cannot be guaranteed. This should always be reflected in ads for weight-loss and slimming products and that is why the advertising rules say you cannot state or imply that dieters can’t fail to lose weight when using your product, or that weight loss is permanent.

+ Read more - Show less

Latest rulings

Menwell Ltd t/a Voy
- Upheld
- Email
- 27 May 2026
Three emails for an online pharmacy promoted prescription-only medicines to the public against the law and our rules. The ads were also socially irresponsible by creating an undue sense of urgency for people who were considering medicated weight-loss programmes.
Health Bridge Ltd t/a Zava
- Upheld
- Website (ad feature)
- 18 February 2026
An advertorial promoting medicated weight-loss seen on the Mumsnet website didn’t make it clear it was an ad, used healthcare professionals to endorse a medicine and promoted prescription-only medicines to the public, against the law and our rules.
Health Bridge Ltd t/a Zava
- Upheld
- Social media (influencer or affiliate ad)
- 11 February 2026
An Instagram post, TikTok video and a Facebook post for weight-loss injections promoted prescription-only medicines to the public, against the law and our rules.
MedExpress Enterprises Ltd t/a MedExpress
- Upheld
- Social media (influencer or affiliate ad)
- 11 February 2026
Three Instagram posts and a TikTok video for weight-loss injections promoted prescription-only medicines to the public, against the law and our rules.

View all rulings

Weight and slimming

Helpful information on the advertising rules for weight-loss and slimming products and examples of previous Advertising Standards Authority rulings in this area.

Latest news

Avoid a false start with our sports supplement marketing tips

ADHD References in Ads

International Women’s Day 2026: Progress, portrayal and the CAP Code

Is your advertising for your dermal patches coming unstuck?

Don’t weight to get your gym ads into shape

Weight-loss and detoxing: Cut out the bad stuff and ensure a balanced diet of responsibility and evidence

Latest rulings

Menwell Ltd t/a Voy

Health Bridge Ltd t/a Zava

Health Bridge Ltd t/a Zava

MedExpress Enterprises Ltd t/a MedExpress

Help getting it right

Popular advice

Multi-Level Marketing

Weight control: Food and Food Supplements

Weight control: Prescription-only medicines

Relevant codes

12 Weight control and slimming

13 Weight control and slimming