A fitness expert with clients including the actors Saoirse Ronan and Michael Fassbender says he is seeing an increasing number of people presenting with "serious metabolic damage" caused by the extreme diet advice from social media influencers.
Paul Byrne received a standing ovation at the Health and Fitness Awards at the Mansion House last week when he called for regulation to protect young people from unqualified bloggers dispensing dangerous advice on fitness and nutrition.
Mr Byrne told the Sunday Independent that people coming to see him had done serious metabolic damage to their bodies. Metabolic damage is the permanent metabolic slowing after dieting. He said: "They are seeing influencers putting photos of their six-pack on Instagram but that is the kind of body a competitor has when they are on a 12-week rigid food plan, competing in fitness competitions. It is completely unsustainable and unhealthy long term.
"That's what I look like when I am going to compete for one day - but then I go back to normal healthy life.
"Everyone now seems to think you can look 'contest ready' all the time but it is not realistic. They are eating turkey and broccoli around the clock and then the binges are biblical. It's like putting on a pair of high heels to look taller. Sooner or later, you're going to have to take them off again."
Mr Byrne said people greatly restrict their diet from Monday to Friday; then from Friday to Sunday they consume more than they do all week and can't understand why they aren't losing weight.
"They can't control themselves after starving for most of the week and then they beat themselves up and the cycle starts all over again on the Monday," he said.
He said many influencers and bloggers have no stress, no mortgages and are young. "This is what they do 24/7. But their diets are not for people with 9-5 jobs in the real world. People who try to follow their diets in the real world can't function, they have no energy, they have no concentration and they are just crabby and grumpy people to be around from not eating.
"My professional clients, in particular, need carbs if they want to focus and concentrate in their work."
Mr Byrne knows one client "whose daughter went anorexic from what she was seeing online. She was so afraid of putting on weight". In another case, a student "resorted to taking steroids because of the pressure he felt watching social media".
He added: "I have an older market but I have had clients whose sons and daughters are bringing in pictures from social media and showing me who they want to look like.
"You could have a skinny marathon runner trying to look like 'The Rock' or others asking if I can help them get down to 3-4pc body fat because they have read it on Instagram, but it's not healthy.
"It's like walking into a tailor's shop and seeing David Beckham in a suit and saying 'I want the exact same'. Just because it looks good on him, if you're not the same shape, it's not going to work."
He said that when people starve themselves, it can lead to metabolic damage and eventually "it opens the floodgates. The body says 'you starved me, I'm going to store it up now'."
Mr Byrne - who turned 50 this year - recently secured fourth place in the men's physique category in the Mr Universe contest, competing against competitors in their 20s.
With more than 30 years' experience in fitness and nutrition, as the head of BodyByrne Fitness, he has won five Mr Ireland titles at the body-building championships and holds a European third Dan Black Belt.
Speaking at the awards, Mr Byrne called on the industry to introduce an award for a gym, club, or chain that exemplifies integrity. This would send a message to an industry which he says "has been hijacked by social media influencers giving extremely unhealthy advice".