The 28-year-old Princess-to-be is an avid athlete, having rowed the English channel for charity in 2007.
US site Radar Online reports that Kate has now started a daily hour-long workout consisting of cycling, jogging and weight lifting.
She is also planning to hit the slopes this winter with her husband-to-be. The couple have enjoyed many ski trips together over the years, both at the Royal family’s favourite resort, Cloisters in Switzerland, and with Kate’s parents in France.
Radar also claims that Kate and her mother Carole are followers of the Dukan Diet, a weight loss plan favoured by celebrities such as Jennifer Lopez and Gisele Bundchen.
Developed by French nutritionist Dr Pierre Dukan, the plan has been described as a low-fat version of the Atkins diet, with followers sticking to high-protein low-carb meals.