However the chain has insisted that the Original Recipe chicken, which is created using 11 herbs and spices, will not change.
KFC says it aims to reduce calories per individual serving by 20 per cent by 2025.
KFC has made the announcement now to allow time to test various methods to reduce the number of calories in the current menu without compromising on taste.
Nutritionist Victoria Robertson, who is working with KFC as its new head of food innovation, said: "We know people are more passionate than ever about eating well, and we face a big challenge in shifting their perceptions of what we offer.
"We've done it before, though – the success of our Riceboxes has shown that our fans will go for lighter options from us.
"That said, we know any new menu and recipe changes will have to be just as tasty as today. It's a tricky challenge, because our fans absolutely love our Original Recipe chicken, and we won't be changing the Colonel's secret recipe of 11 herbs and spices.
"This is about providing choice, and offering delicious, signature KFC taste that just happens to be lighter."
It's unclear if or when the changes will affect New Zealand.