LONDON (REUTERS, BLOOMBERG, THE GUARDIAN, NYTIMES) - Willy Wonka's big idea was the ever-lasting gobstopper.

Nestle has gone one better: low-calorie Kit Kats. The Swiss food company, which is the world's largest packaged food group, said this week it has found a way to cut the amount of sugar in chocolate by as much as 40 per cent.

The maker of Kit Kat and Aero bars said its researchers have found a way using only natural ingredients to change the structure of sugar particles.

"It is sugar, but it is assembled differently so it can disassemble easily in your mouth with less going into your gastrointestinal tract," the company's chief technology officer, Dr Stefan Catsicas, said in a statement late on Wednesday (Nov 30).

Nestle declined to fully explain the process, because the company is pursuing patents for it. But Dr Catsicas compared a normal crystal of sugar to a shoe box, where the box is made of sugar and everything inside it is also made of sugar.

The new sugar, he said, will be processed to have the same sugar exterior - though it may be a globe instead of a box - to dissolve in the mouth. Because less sugar is inside, less goes to the stomach.

The announcement comes as a global obesity epidemic ramps up pressure on processed food makers to make their products healthier. Nestle and its peers have all been working to reduce sugar, fat and salt, as consumers increasingly opt for fresher, healthier options.

A four-finger milk chocolate Kit Kat currently contains 23.8g of sugar and a medium peppermint Aero has 24.9g of sugar. If the amount of sugar in each of these products was cut by 40% the new amounts would be 14.3g and 14.9g respectively.

Nestle said it was patenting its findings and would begin to use the faster-dissolving sugar across a range of its confectionery products from 2018.

Nestle is not the first company to experiment with designer molecules.

PepsiCo in 2010 piloted a designer salt molecule that it said would allow it to use less sodium without affecting the taste of its snacks, which include Walkers crisps and Cheetos.