Gwyneth Paltrow has said a cleansing diet once left her hallucinating for 10 days.
The Iron Man 3 star is famed for her healthy lifestyle but in a column she wrote for the Daily Telegraph she admitted it didn't always have good effects.
She wrote: "I've done juice cleanses in the past, and in my 20s I did the Master Cleanse, which left me hallucinating after 10 days. Be aware: a juice detox can crash your metabolism and lead to future weight gain."
Mum-of-two Gwyneth also wrote that she thought women should ditch the scales.
She said: "There is something punitive about weighing yourself. It can leave you vulnerable to shame and guilt, and it messes with you psychologically. Women naturally gain and lose weight during their monthly cycle anyway, so it can be more realistic to monitor your body shape with a measuring tape."
Gwyneth advised Telegraph readers to allow themselves the occasional bad treat, saying: "Allow yourself programmed treats - I often have a glass of red wine in the evening and smoke a cigarette on a Saturday. I love those moments because they are just the right amount of naughty. That balance keeps you vibrant. You have to live your life, after all."
The 40-year-old actress recently offered her beauty advice to Cosmopolitan, too.
She said: "I don't like Botox. I think on some faces it works, but it's when you can really see it that it starts to look fake. I love how French actresses age but don't really do anything about it - it's beautiful."