The 27-year-old presenter - who has gained and lost weight a number of times in the past - is reportedly staying slim with the technique as people eating from a plate the same colour as their food is believed to increase what they eat by 20%.
A source told Now magazine: "Five months after Kelly started the plan the results are there for all to see. She thinks it's amazing - she takes her plates everywhere. Unlike other fads, Kelly says this diet does help you lose weight and keep it off."
Osbourne lost 60lbs in two years and has recently been able to wear T-shirts designed for children.
She said: "People have this idea that I'm large and they don't realise I am 5ft 2in and a UK size 6-8. I go to GAP Kids for T-shirts.
"I've done all the faddy diets and none of them work. On one, I had to drink this diet shake for a week. It promised I'd lose 10lbs but I just felt sick."