The Eating Disorder Association of Ireland, Bodywhys, has said it has a number of "concerns" surrounding the return of RTE Operation Transformation.
The show, hosted by Kathryn Thomas, is back on our screens on Wednesday night.
But it has been criticised in the past for the attitude towards weight and food displayed during it.
And, in a lengthy statement on social media, Bodywhys said they had received a "great deal" of concern about the return of the reality show.
They wrote: "Bodywhys, the Eating Disorders Association of Ireland, has received a great deal of correspondence and concerns, which we share, regarding the programme 'Operation Transformation', set to return to RTÉ on January 5.
"Many of our service users have highlighted that the show has been and continues to be triggering for them, causes them distress and impacts negatively on their mental health.
"This is, in particular, for those who have or live with a person with an eating disorder, or those experiencing disordered eating.
"Although the show has a positive objective intending to bring focus to health and well-being, the considerable emphasis on dieting, body weight and shape and the way these are measured, collectively counted and presented, create a community sanctioned dieting culture that research shows does little to achieve long-lasting weight loss or health promotion."
Bodywhys noted that it had contacted the producers of the show to ask for a more "inclusive approach" and requesting a disclaimer around the content of the show.
The statement continued: "Anecdotally, we have heard that when the show is broadcast, a wave of pressure and conversations about food, calories, eating behaviours and exercising emerges in homes, workplaces and communities, where health messages become conflated with discipline and a numbers game that is unhelpful at least and damaging at worst.
"Faced with this growing problem, programmes that are supported by public health initiatives need to take account of the audience they are broadcasting to, and ensure that they have appropriate signposting information at the very least. It is important that we are all aware of the impact this pressure can have on people of all different age groups and backgrounds in our society."
RTE has been contacted for comment.
