Obese children as young as three years old are suffering from bone breakages and arthritis.
Their weight is having an impact on their joints, a new study has revealed.
"A high intake of sugar-sweetened beverages and fizzy drinks weakens the bones, so if you fall, you fall with greater force and the bones break," said Grace O'Malley, a senior physiotherapist at Temple Street Children's University Hospital.
"Children are [also] not getting enough vitamin D, so you have a perfect storm," she said.
"I'm seeing the signs of these effects every day and we're not doing enough to protect the most vulnerable," she added.
"Some of the children's parents don't know that fizzy drinks are bad for them so there is a huge parental and societal responsibility involved in all of this."
The physiotherapist was one of the authors of a study carried out by Temple Street that looked at the prevalence of musculoskeletal impairments in obese children attending the hospital's weight management programme, called W82Go.
"It's shocking to see on paper that nearly 90pc of children have movement disabilities," Ms O'Malley stated.
"All the children we see in the clinic are defined as clinically obese and their weight is having an impact on their joints.
"We see juvenile arthritis anyway, but what we're seeing with these kids is a lot of inflammation in their body because of all the fat tissue.
"They tend to get pain on the inside of their knees. We don't know if that's going to lead to osteoarthritis further down the road, but it certainly increases the likelihood of these children developing that very early," the expert warned.
As part of the study, a total of 178 children and teens aged between three and 18, who are attending the W82GO programme, were monitored for musculoskeletal impairments.
Their pain levels, balance, flexibility and gait were tested by researchers.
The findings showed that nearly 90pc of the group had musculoskeletal problems.
Just over half (51pc) reported pain, while 69pc were attending orthopaedics and 30pc had attended accident and emergency departments for their ailments.
The study recommended that each child attending the clinic be screened for barriers that may limit physical activity.
There are an estimated 300,000 overweight and obese children in Ireland. Around 70,000 are classified as clinically or morbidly obese.
Temple Street hospital's programme costs just €600 to treat one child. However, adult obesity costs the State €1.6bn annually.