Adele's personal trainer has revealed the brutal diet that led to the hit singer's incredible 45kg weight loss.
At the beginning of January, photos emerged of the Hello hitmaker sporting a considerably smaller frame while enjoying a vacation with celebrity pals Harry Styles and talk show host James Corden in Anguilla, an island in the Caribbean.
She was spotted by fans enjoying herself on the beach, and revealed she has lost around 45kg.
"At first we barely even recognised her because she lost so much weight," 19-year-old fan Lexi Larson told PEOPLE magazine, after meeting Adele at a restaurant in Anguilla.
"She told us she lost something like 100 lbs [45kg], and that it's such a crazy positive experience."
While Adele hasn't publicly commented on her weight loss, she did allude to her new, healthier lifestyle on Instagram back in October.
She captioned a photo of herself: "I used to cry but now I sweat."
Camila Goodis, a PT and pilates instructor based in Los Angeles who trains Adele, explained that while the 31-year-old has definitely embraced exercise, her weight loss is mainly due to her strict diet.
"She looks amazing, she changed her lifestyle, she changed her diet," Camila said on UK breakfast show Lorraine.
"I believe now she's into working out, she's working out more and more but, it's 90 per cent what she did was diet. There's no secret, I didn't help with any diet. She started doing this certain diet and now she's maintaining just eating healthy. It's a good diet to shed the weight," Camila said.
And she revealed exactly how many calories Adele was eating in a day at the start of her weight loss journey - and the number might shock you.
"The first week is pretty intense ... it's a lot of green juice and 1,000 calories a day," she revealed.
"Giving up processed food, sugar, soda and get into an exercise routine, like cardio and strength training, will change people's bodies."
1000 calories is the equivalent of 4184 kilojoules. According to established health guidelines, the average Australian should eat around 8700 kilojoules in a day, but considerably less if they are looking to lose weight.
But some of Adele's fans are worried that her diet is too restrictive - and even dangerous.
"1000 cal per day is not sustainable and you don't need a personal trainer for this," one fan wrote on Instagram.
Another said: "I would be more wowed if these results would have been reached through clean eating with normal calorie intake and training... I am not a professional trainer, but I am qualified enough to know that this is not a very healthy way of losing weight... this is just my opinion for this you don't have to be a guru... Love Adele either way, but in her new pics she looks tired 🤔"
A third person wrote: "Adele is gorgeous as always regardless of her weight ❤️"
But sources close to Adele say her new transformation isn't just about losing weight and looking skinny.
"You see, her new look is as much, if not more, a mental thing as it is physical," a source told PEOPLE magazine
"It's easy to just focus on her physical transformation, but this is really about something bigger. She got to the point where she didn't feel great. 'She knew she had to change something because she wants to be the healthiest mum possible."
Adele has a seven-year-old son, Angelo, with her ex-husband Simon Konecki.