Low-carb diets have been around for a while, but the keto diet has taken things to a whole new level, and experts warn it's causing serious problems for gut health.
As millennials look to avoid carbs altogether as part of keto's high fat, low carbohydrate recommendations, a high number of young people have expressed symptoms relate to low fibre intake.
A survey in the UK found more than 67 per cent of millennials have been experiencing stomach issues such as bloating, constipation and diarrhoea. The number is more than double that of adults of all ages, with only 33 per cent from older generations experiencing these same issues.
A huge three quarters of those young people suffering stomach problems said it was negatively impacting their wellbeing and day-to-day mood.
The Happy Gut Survey, commissioned by Kellogg's, found 55 per cent of people felt they were meeting their daily fibre requirements, but in fact only eight per cent were actually hitting the target.
Registered dietician, Jo Travers, is the author of The Low Fad Diet. She told the Daily Mail: "The trend towards diets that restrict carbs, such as the millennial-favourite keto regime, also means considerably restricting fibre intake.
"This is not only highly concerning for the increased risk of coronary diseases but also for the gut which needs dietary fibre to nourish its good bacteria.
"With emerging bodies of research showing the impact the gut has on our overall health and emotional wellbeing, looking after it with nourishing fibre-rich foods is extremely important and carb-cutting is therefore ill-advised."
According to a separate survey by the International Food Information Council (IFIC) and Insider magazine, around one in six people aged 18 to 34 are on a low carb diet, and one third of millennials said they would like to be on one.
The IFIC deduced the reason was around a quarter of all consumers believe eating carbohydrates is directly linked to gaining weight.
Matt Perkins, nutritionist for Kellogg's, said: "The most common issues with a diet lacking in fibre are the least glamorous.
"Symptoms such as sluggish bowels, constipation, and runny stools can all mean you're not getting enough – making you feel lethargic and generally feeling miserable."
Fibre can be found in a range of foods, such as whole grains, potatoes and kumara, as well as in most fruit and vegetables.