They are the supermodels of the animal world, shunning sweet food in favour of the feline version of the Atkins diet.
Lions, like moggies, don't like sweets
Now, scientists have discovered why cats prefer dining on meat and fish - they cannot detect sugary foods due to a defect in a key taste receptor gene.
Molecular analysis shows big cats also have the faulty gene, and this probably helped shape the evolution of their carnivorous behaviour.
The research is published in the journal known as PLoS Genetics.
It has been a mystery for years why domestic cats, along with lions, tigers, leopards and jaguars, dislike sweet-tasting foods.
This is unusual in mammals, so US and UK scientists decided to look at whether the genes coding for the receptor that detects sugars and sweeteners might be defective in cats.
They looked at the two cat sweet-receptor genes to see if there were any "mistakes" in the DNA code.
"Lo and behold, there was a defect," said Leslie Stein of the Monell Chemical Senses Center in Philadelphia, Pennsylvania, US.
"The reason that they don't care about sweet foods is because they can't taste them. Sweet taste is meaningless to them."
Low carbs cat: On the prowl for protein
This makes sense in evolutionary terms, since, in the wild, cats exist on a high-protein meat-packed diet, with very little carbohydrate.
It also shows that genetic influences on taste play a role in food selection and nutrition, in both humans and animals.
"We probably all have individual variations in our taste-receptor genes," said Leslie Stein. "We probably all have a unique way of tasting and smelling the world."
The study in PLoS (Public Library of Science) Genetics is collaboration with the Waltham Centre for Pet Nutrition in Melton Mowbray, Leicestershire, UK.