Beyoncé. Picture: Instagram

London - Earlier this year, pop queen Beyoncé posted a new video to social media with footage from rehearsals for her celebrated 2018 appearance at the music festival Coachella.

It was less than a year since she’d given birth to twins Rumi and Sir, and she needed to get back into those trademark sequins in time for the gig. We see her famous feet approach the scales - "every woman’s nightmare" she whispers, stepping on - before revealing a weight of 175lb (over 79kg). "Long way to go," she mutters. "Let’s get it."

Cut to the man she turns to - Marco Borges, "exercise physiologist" and nutritionist to the stars, who in 2013 put Queen Bey and husband Jay-Z on a radical vegan diet and has ever since been on speed dial chez Knowles-Carter.

In the video, we see him personally overseeing Beyoncé’s diet and exercise regime, and almost before you can whip up an almond-milk smoothie and top it with broccoli, she’s back on stage looking fab in sparkly Lycra.

WATCH: Beyoncé's 22 Days Nutrition plan

It is, of course, the best advert for Borges’ methods you could possibly have crafted, with more than 19 million people viewing the video within 24 hours of its posting.

It is clearly no coincidence that Borges has a book to sell - Greenprint, which describes in detail the "22 Laws" behind his manifesto for plant-based living, the "22 Day Nutrition Plan", a figure chosen because apparently it takes 21 days to break bad habits and form better ones.

Beyoncé followed the diet for 44 days, in fact. 

Yet the backlash was swift, with some accusing Beyoncé of "body shaming" women who weigh more than 79kg.

Others wondered aloud whether Borges’ diet and lifestyle plan, which involves no bread, no carbs, sugar, dairy, meat, fish or alcohol and is also followed by actress Jennifer Lopez and singer Pharrell Williams, was too restrictive for mere mortals without personal chefs.

Dieticians, meanwhile, questioned the low calorie count - 1 400 a day, according to the British Association for Nutrition and Lifestyle Medicine. 

Is it really healthy only ever to eat plants? Not even honey, since, like cow’s milk, that breaks one of Borges’ cardinal rules: don’t eat any product from a thing "with a face".

As for accusations that his diet is too restrictive, Borges says they come from people who simply don’t understand his regime, and indeed his book devotes many pages to sources of vegan protein, iron and other vitamins and minerals (while also admitting he takes a daily B12 vitamin supplement himself).

Daily Mail