From celebrities such as Miley Cyrus and Matthew McConaughey to our best mates and hairdressers, it seems like everyone has tried out the Paleo diet.
For those uninitiated, the diet - nicknamed the caveman diet - is a nutritional plan based on the presumed diet of Paleolithic people. It categorises food under three groups: foods to eat liberally, foods to eat in moderation and foods to avoid.
Followers are required to avoid dairy, grains, pulses, sweeteners and processed foods all together.
But a leading anthropologist has now said the core principles of the diet are flawed. The Paleolithic wouldn't have eaten the Paleo diet as we know it.
According to Ken Sayers, a human evolution expert from Georgia State University, cavemen would have eaten some of the banned foods.
Diets 2.6 million years ago would have varied from location to location, with humans eating whatever food they could find to gain the highest amount of energy with the minimum amount of effort.
“Hominids didn’t spread first across Africa, and then the entire globe, by utilizing just one foraging strategy or sticking to a precise mix of carbohydrates, proteins, and fats,” he wrote on The Conversation. “We did it by being ever so flexible, both socially and ecologically.”
Speaking to HuffPost UK Lifestyle, British Dietetic Association spokesperson Duane Mellor confirms that early humans would have eaten "what was available".
"They would definitely not have followed any rules to avoid certain food groups like dairy or gluten, if they were available they would have been eaten," he adds.
"The key message and perhaps a caution, is our ancestors would have evolved and adapted to any and all food that would have been available, today the availability and reliability of our food supply means it is increasingly easy to over-consume especially highly palatable processed foods high in fats and sugar."
Mellor says some aspects of the Paleo diet, such as eating more fresh foods and a variety of fruit and vegetables, is sensible.
"However, promoting a belief that such a diet was based on strict exclusion-based rules, is a myth and potentially harmful as it could promote disordered patterns of eating," he says.
Nutritional Therapist Karen Poole points out that the Paleo diet leads people to reduce carbohydrates, potential allergens, trans/hydrogenated fats and added salt, so on the surface it could help limit the risk of heart disease, diabetes and obesity.
"However, I wonder how it would work in the long-term as a sustainable diet," she previously told Sport and Fitness.
"Over time a reliance on meat and fish protein could run the risk of raising your acidic ph levels that may bring a whole host of health implications such as low immunity, impaired digestion and fatigue."
It seems that moderation is key for people attempting to lose weight in a healthy way. Some aspects of Paleo may be beneficial, but some may not.
The important thing is to speak to your GP and find a diet that works well for you, regardless of whether or not it worked for your ancestors.