So what is the secret behind £90million Adele's sleek new look? Buckwheat, kale and plenty of cups of green tea!  

By Laura Lambert and Sam Creighton for the Daily Mail

Published: 00:04, 24 May 2016 | Updated: 00:06, 24 May 2016

She once declared she would never lose weight because of pressure from the music industry.

But as it was reported that she has just signed a record-breaking £90million deal, Adele was doing a very good impersonation of someone on a diet.

Accepting one of five accolades at the Billboard Music Awards, the singer looked stunningly svelte – a contrast to the curvier look she sported when she first found fame. 

Accepting one of five accolades at the Billboard Music Awards, singer Adele looked stunningly svelte – a contrast to the rather curvier look she sported when she first found fame

Accepting one of five accolades at the Billboard Music Awards, singer Adele looked stunningly svelte – a contrast to the rather curvier look she sported when she first found fame

The Mail can today reveal the secret behind this weight loss: The Sirtfood Diet and a fitness plan from trainer Pete Geracimo – whose clients include David Hasselhoff and Kim Cattrall.

The diet, which Mr Geracimo recommends, encourages slimmers to eat plant foods, such as kale and buckwheat, known as sirtuin activators, which suppress appetite and activate the body's 'skinny gene'.

This is the same process caused by fasting or exercise and the sirtuins – also known as 'housekeeping genes' – help control the way our bodies handle fat and sugar, regulating appetite as a result.

The eating plan complements a gruelling gym regime and sees Adele consume the likes of green tea, cocoa powder and turmeric, that are high in sirtuin activators.

Adele poses with her Oscar for Best Original Song for 'Skyfall' at the 85th Academy Awards in 2013

Adele poses with her Oscar for Best Original Song for 'Skyfall' at the 85th Academy Awards in 2013

Anyone who has followed Adele's career will notice that her transformation goes far further than her new designer wardrobe, with her face looking considerably thinner than just a few years ago.

Her waistline is also the smallest it has been in years – her new video let her show off her enviable physique from every angle. 

But, anyone worried the singer, 28, is being pressured into starving herself in the name of beauty can rest easy: The diet still allows her to indulge in her favourite red wine and cheese.

A source said: 'The Sirtfood Diet is all about losing weight and feeling fantastic through eating great-tasting food. It's based on extensive research into the power of key plant foods, which when added to our diet turn on fat burning and improve wellbeing.'

The results were plain to see at Sunday night's glitzy award ceremony, when Adele collected her five gongs via video. However, this latest success was not the only reason she had to celebrate yesterday.

Her waistline is also the smallest it has been in years – her new video let her show off her enviable physique from every angle

Her waistline is also the smallest it has been in years – her new video let her show off her enviable physique from every angle

She is reported to have signed a £90million contract with Sony records, the biggest record deal in history for a British musician.

She was the best-selling artist in the world in 2015 but her contract with British independent label XL, who she signed to at the age of 19, expired this year and it is believed she has been poached by Sony

The lucrative deal will double Adele's £85million fortune, which includes more than £35million in sales from her latest album, 25.

Adele once declared: 'I'm not going to lose weight because someone tells me to. I make music to be a musician, not to be on the cover of Playboy.' However, her new healthy figure must surely be a badge of pride.

Speaking about getting in shape for her world tour, she said: 'I was trying to get some stamina…so I lost a bit of weight… not to be like a size zero or anything like that. I mainly moan. I'm not skipping to the ****ing gym. I don't enjoy it.'

SLIMMERS CAN LOSE 7LB IN SEVEN DAYS ON SIRTFOOD DIET

The Sirtfood Diet counts professional athletes and chefs among its followers, including Anthony Ogogo and Lorraine Pascale.

It works by using everyday plant foods, known as sirtuin activators, which switch on the body's 'skinny gene', the same process sparked by fasting and exercise.

This sees slimmers burn fat, increase muscle mass and improve health. The diet has been devised by nutrition experts Aidan Goggins and Glen Matten and has two distinct stages.

The first is an intensive seven-day programme designed to kick-start weight loss and which can see the average person shift seven pounds. This is then followed by a second stage designed for sustained weight loss.

Although sirtuin activators are found through the plant kingdom, only certain fruits and vegetables have large enough amounts to count as sirtfoods. 

These include olives and extra-virgin olive oil, onions, kale, parsley, blackcurrants, tofu, capers and cocoa.