Emma Thompson has dropped two dress sizes in six weeks thanks to Kate Middleton’s personal trainer.

The 57-year-old Oscar winner has embarked on an ‘anti-diet diet’ – involving no fad foods such as chia seeds, kale and gluten free items – with the help of the Duchess of Cambridge’s dietitian, Louise Parker.

Costing £4,500 for a six week intensive course, which sees clients training six times a week for 90 minutes at a time, Miss Thompson lost around 8kg, going from a size 14 to 10.

Unlike many clean eating regimes, the trainer’s method includes bacon sandwiches, cheese, steak burgers and - in the particular case of her Hollywood devotee - even the odd glass of picpoul de pinet.

In the foreword to her healthy eating book, The Louise Parker Method: Lean For Life: The Cookbook, the Love Actually star writes: ‘Louise is the only one out there I trust - she’s not holier than thou, yet somehow miraculously gets my reluctant arse into gear and sometimes even keeps it there.

‘I love that her method is NOT a diet - and is genuinely sustainable - so I can have my glass of wine and manage to avoid spending the rest of the week eating cheesy Wotsits.

‘She toughens me up without driving me round the bend with kale juice and the more depressing style of sprout. She just gets it. We all use her, because she’s discreet and funny and that’s really important.’

So what is the diet?

Described by Parker herself as the “anti-diet diet”, the plan takes a holistic approach to weight loss and is focused on managing stress, consuming a balanced diet of high-quality ingredients and exercising every day.

You can try a more stream-lined version of the method from home which is covered in her books – The Louise Parker Method: Lean for Life and The Louise Parker Method: Lean for Life: The Cookbook. Louise’s global team of dietitians has more than 11,000 devotees in 48 countries.

“My method is about more than just losing weight,” the health guru writes. “It’s about living a lifestyle that sustains you in optimum health, peak performance and clarity of mind so you are absolutely brimming with vitality. The side-effect of this lifestyle is that your body will transform into one that is exceptionally lean, sculpted, strong and graceful.”

For the first six weeks, the “transformation phase” involves “thinking successfully” – adopting a positive mental attitude and visualising your goals, “living well” – completing a digital detox every night after 9pm, sleeping 7-8 hours per night, and grabbing 20 minutes of downtime per day, “eating beautifully” – three meals and two snacks a day with each meal comprising lean protein, healthy fat and vegetables, and “working out intelligently” – by introducing exercise into your everyday, with a minimum of 10,000 steps per day and for at least 15 minutes a day.

The Lifestyle Phase is about sustaining your new way of living. The idea is that the Transform Phase will have changed your habits, so although no foods are on the must-not eat list, you’ll have been armed with the ability to decide whether any sugar-cravings are worth the consumption.