An advertising watchdog has upheld a complaint about an advert for the Atkins diet which claimed it helped people have a healthier lifestyle.
Red meat is a key part of the Atkins diet
The UK's Advertising Standards Authority ruled the claim could not be proven and should be removed.
The ASA also ruled that the low carbohydrate plan conflicted with government advice on a balanced diet.
The Atkins company defended its diet as "scientifically validated".
The advert at the centre of the complaint, which had featured in regional press, showed pictures of Atkins-branded foods with the statement "Atkins the original low-carb lifestyle".
The company provided 44 scientific studies to support its "healthier lifestyle" claim.
But the ASA found the studies were either carried out over short periods of time or were limited in their scope. Several called for longer assessments to be carried out.
The Atkins Nutritional Approach claims to be a "lifetime nutritional philosophy".
On its website, it advises dieters to cut down on refined carbohydrates such as high-sugar foods, breads, pasta, cereal and starchy vegetables.
But the ASA found that "... the plan conflicted with UK Government advice on achieving a balanced diet, which among other things stated that starchy foods should make up about one-third of people's diets."
It ruled that any future Atkins advertising should be on an "availability-only" basis until the advertiser could prove its health claims were true.
The Atkins website states that its branded products are on sale in more than 1,000 British stores.
The company, founded in the US in 1989 as Atkins Complementary Formulations, produces low-carb foods and other diet supplements.
The UK wing of its operations went into administration earlier this year.