More than 400 people were hospitalised with obesity in 2018 and 2019.
Freedom of Information figures, released to Newstalk, show that 187 people were admitted to hospital with the condition last year.
That was down on the 218 who were admitted in 2018.
Nearly two-thirds of the patients over the last two years were women and one-third were men.
Professor Niall Moyna from the Department of Health and Human Performance at DCU said there needs to be a greater focus on the causes of obesity.
“We know that people who come from lower socio-economic backgrounds are at much higher risk of developing obesity,” he said.
“Almost one in ten three-year-olds in Ireland who come from lower socioeconomic backgrounds are obese, where it is only one-in-20 of those coming from higher socio-economic backgrounds.
“So, things like conditions of birth and during early childhood, education, access to employment – people underestimate the importance of those determinants and how they impact on our health.”
He said patients who are admitted to hospital with obesity would be seriously ill.
“If you get to the stage where you have been admitted to hospital, it is likely that you have developed some comorbidity associated with your obesity and that is the reason for your hospitalisation,” he said.
“It could be high levels of blood glucose, it could be renal problems, it could be high blood pressure – because we know that when someone becomes obese, there are an array of problems that follow with that.”
Reporting from Eoghan Murphy