The mantra of 'move more and eat less' does not apply to many people struggling with obesity, according to a leading doctor.
Today marks World Obesity Day, with health agencies and organisations calling for a cohesive, cross-sector response to the obesity crisis.
One-in-eight people globally are now living with obesity, the World Health Organisation has said.
Obesity among adults has more than doubled since 1990 and has quadrupled among children and adolescents aged five to 19 years.
In 2022, being overweight affected around 37 million children under five, and over 390 million children and adolescents, including 160 million who were living with obesity.
Data also shows that 43% of adults were overweight in 2022.
On The Pat Kenny Show Trauma and Orthopaedic Surgeon Professor John O'Byrne set out the impact obesity can have on your body.
"The effects of having a massive amount of fat tissue are not just weight-related," he said.
"Obviously if you're carrying around a huge amount of weight, you're putting extra forces through your joints.
"But there's a separate effect of excess fat tissue and that's an inflammatory effect, which is realised that it can cause arthritis in non-weight bearing joints.
"For example, patients who are living with obesity get lower limb arthritis, particularly knees and foot and ankle problems, but they also get osteoarthritis of the hands.
"Somebody who's living with obesity is not comparable to you just putting on a really heavy body suit and carrying that around".
More damage from falls
Prof O’Byrne said weight can be good in the sense that it loads tissue and makes it stronger, but this is not the case for everyone.
"Patients who have a very high BMI, their bones are obviously carrying more weight but they don't get as strong as you would expect," he said.
"They get marginally strong but certainly not in correlation with the excess weight".
An obese child holds a doughnut, 16-7-16. Image: Kwanchai Chai-udom / AlamyProf O'Byrne said heavier people are more like to injure their joints.
"They are more prone to falls and the falls are more significant because of the weight going through the bones as they fall," he said.
"They get worse fractures, they're less agile [and] they're less able to right themselves.
"They fall more heavily; the fractures they get are more complicated.
"Children, for example, who are living with obesity, if they fall... the bone breaks into more pieces, if you like, and it is more likely to be displaced."
Prof O'Byrne said when children fall on their hands the bone usually heals back in place, but that is not the case with heavier children.
"If it is a patient living with obesity and they fall on the hand, they will displace that fracture - so it is in a position that is not acceptable".
Prof O'Byrne said that any procedure to fix these fractures can present complications around the use of anesthetic, a patient's airwaves and any potencial surgery - but that "there's been huge improvements" in this area.
'Baseline energy'
Prof O'Byrne said the mantra of 'move more and eat less' is not something obese people should live by.
"Your body uses a certain number of calories for your heart to beat, your lungs to breathe and your kidneys to work - they're baseline energy that you use," he said.
"If you are somebody living with obesity and not moving at all, you are using a lot of energy on those processes and you're very inefficient at them.
"But then if you start to move for sure you're using calories in your movement, but those processes become more efficient so they use less calories.
"So now you're using less calories on the body functions... so the calorie usage there goes down.
"In fact, after an initial surge the net amount of calories equalises," he added.
Prof O'Byrne added that while large amounts of food can lead to obesity, diet alone for those who live with the condition "doesn't work".
