Her Majesty avoids rice, potatoes and pasta at night.
Kate is also a big fan of exercising, helping to keep her slender.
Speaking to Mail Online, a source gave a look into the exercise plan she has followed in the past.
They told the publication: “Kate is an exercise junkie. Pippa and Kate take their toned physiques extremely seriously.
“She and Pippa enjoy strenuous make-up-free aqua aerobics sessions and larky water polo with William and Harry.”
Want a flat stomach like Kate Middleton’s?
A five-minute at-home workout plan provides easy exercises for flat abs.
While going to the gym may be out of the question, an expert revealed some moves that can be done at home to tighten the core.
Krissy Cela, the founder of Tone & Sculpt, shared her top five moves for a slim waistline with Express.co.uk.
The workout can be completed in as little as five minutes and repeated for the best results.
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