It's a divisive diet trend. Paleo eating is all about meat, veggies and absolutely no carbohydrates. It's based on how cavemen used to eat.
But new research has called into question the popular diet's very foundation, revealing carbs were an important part of human evolution.
It's been the world's most-Googled diet for the past two years, and thanks to celebrity chef endorsements, paleo's popularity continues to rise.
Also known as the caveman diet, paleo eating involves grass-fed meat, fruit, veggies, nuts and seeds. Dairy, processed foods, sugar, grains and carbohydrates aren't allowed – only foods our ancestors would have hunted and gathered.
But new research published in the Quarterly Review of Biology reveals that cavemen did, in fact, eat starch from plants, packed with carbohydrates.
"We know that there was a variety of foods eaten way back in the past," says AUT registered dietician Elaine Rush.
She says the human body is designed to digest carbs.
"The shape of our jaw, the sort of teeth we have for grinding food, our molars at the back, they're for eating the carbohydrate, plant-type foods, and also the fact we have enzyme in our saliva and small intestine and pancreas, they're for digesting carbohydrates."
The study also suggests carbs were essential in the evolution of the enlarged human brain.
"The whole grains and carbs have meant that we've been able to survive in times of famine, and that is part of why we are here today – survival of the fittest."
The founder of the paleo movement has slammed the study, saying: "It's best to let the data speak for itself and not let poorly tested hypotheses by charismatic individuals guide the scientific method."
Critics say cutting out an entire food group is dangerous for our health.
The researchers are now calling for carbs to be put back into the caveman diet, the way it was 7 million years ago.