The British Association for Nutrition and Lifestyle Medicine warned that a diet endorsed by US pop singer Beyoncé “could be dangerous.”
The warning was made during a BBC programme.
Nutritionist Daniel O’Shaughnessy warned that the diet could lead to “nutritional deficiencies”.
Subscribers to the 22-day plan pay $14 to access plant-based recipes.
The original diet was created in 2013 but the singer is now promoting Beyoncé’s Kitchen, the plan she followed in preparation for her comeback performance at the 2018 Coachella festival after having twins.
A promotional video released on her YouTube channel last month opens with a clip from her Homecoming film, showing her stepping on to some scales and saying her weight is “every woman’s worst nightmare”.
The video has been viewed 1.7 million times.
Her plan was devised by 22 Days Nutrition founder Marco Borges, whom she describes as her “friend, trainer, exercise physiologist and New York Times bestselling author”.
But O’Shaughnessy questioned its stated nutritional values.
For example, one of the recipes, a “vegg sandwich” containing 36g (1oz) of protein, actually contained just 24g, he said.
While another, a green smoothie, contained eight teaspoons of sugar.