It's often the bride who goes on a health kick before her wedding.
But with an estimated billion people set to watch his nuptials to Meghan Markle next month, it appears Prince Harry has been on one too.
As well as becoming a member of an exclusive gym the sixth in line to the throne has been following his fiancées love of 'clean eating' – and has lost more than half a stone as a result, reports the Daily Mail.
According to one source, the royal has joined Miss Markle, 36, in juicing, cutting out carbs and processed food and incorporating ingredients such as kale and quinoa into his daily diet. A source said: "Meghan has completely changed Harry's diet. She's got him juicing and he has lost at least half a stone, which is a lot for someone as skinny as he is.
"They have bought a top-of-the-range juicer and she has him on fruit and veg smoothies. She's also weaning him off meat."
In recent months, Harry has let slip how much he has cut out of his diet.
On a visit to Chicago school last year, the 33-year-old admitted that he had given up pizza, and told students on another visit that he had never eaten a kebab.
It was a strange assertion since when he was a soldier, colleagues said he "lived off Kentucky Fried Chicken". And his family's former chef, Darren McGrady, said that as young boys Harry and William loved eating burgers, pizza, and potato skins.
Miss Markle, on the other hand, has had her diet and exercise regime down to a fine art for years.
She is a yoga obsessive – her mother, Doria Ragland, is an instructor – who regularly attends classes at a studio in London.
Miss Markle also runs in Kensington Gardens, just as Princess Diana did before her, and does Pilates regularly. At home, she follows a largely plant-based diet, but admits to enjoying French fries, wine and the occasional ice cream.
Miss Markle once described her 'ideal day' as starting with a 'clean cleanse vanilla shake' blended with blueberries, a nicoise salad for lunch, with a little goats cheese and possibly a slice of baguette on the side, with seafood for dinner.
She said: "I try to eat vegan during the week and then have a little bit more flexibility with what I dig into on the weekends. But at the same time, it's all about balance ... I don't ever want to feel deprived. I feel that the second you do that is when you start to binge on things."
Her fridge is usually stocked with hummus, carrots, a green juice, almond milk, and a chia seed pudding she makes every single week.
Reports say that even though she already boasts a model figure, Miss Markle has had to have her wedding dress taken in several times in recent weeks due to her own weight loss.