The HSE's clinical lead on obesity has criticised fast-food chains for making calorie and nutritional information "almost invisible" on their menu boards.
Professor Donal O'Shea wants McDonald's to do more to make information clearly available for customers to help tackle the obesity crisis in Ireland.
Mr O'Shea commended the fast-food chain for taking a lead in the industry by introducing lower-calorie meals but accused McDonald's of "disguising" the calorie content of most of its range.
"I think McDonald's lead these kinds of initiatives, in fairness to them, but they do disguise what the fast food industry is about, which is selling their main products 90% of the time and really disguising the calorie content as best they can, even though they will flagship initiatives like this," he said.
The comments come just days before the closure of a public consultation on legislation which could require all restaurants, bars, cafes and fast-food outlets to display calorie information on menus.
The controversial measures have been criticised by the Restaurants Association of Ireland (RAI), which said it is "outraged" at the proposals.
The group described it as "nanny-statism at its best".
Last month, McDonald's launched a lower calorie ‘Meals Under’ range, saying it strongly believed in "providing our customers with transparent nutritional information in order to help them understand what they are consuming and make informed choices".
A spokesperson for the company has defended their efforts in this area.
"Calorie information is prominently displayed on all self-order kiosks, at meal collection points and on the McDonald's Ireland website. McDonald's self-order kiosks promote healthy alternatives and options for meals, helping customers to make informed choices," the company said.
But Prof O'Shea said, "If you go into McDonald's and try to find out how many calories are in your Big Mac or Grand Big Mac, even though they say they put them beside the price, look at the colour - they make them almost invisible.
"We know that making people aware of calories is important. We know putting them beside the price in the same size as the price and the same font and as remarkable a colour is important."
Prof O’Shea said customers adding options like a sugar-sweetened drink or smoothie to their meal can also bulk up the calorie content very quickly.
This can mean children's meals can often include 700 or 800 calories he told Newstalk's Breakfast show.
"That is way beyond what it should be. We need more and more awareness of that in the middle of the obesity crisis we are in,” he said.
Prof O’Shea said McDonald's is “in the lead in raising calorie awareness but it still isn’t where it needs to be” while the likes of "Burger King and places that refuse to post calories" also need to act.