“Fad diets don’t work, and the public needs to be aware of who they take advice from,” said Louise Reynolds, a dietitian with the institute.
A new worldwide study on obesity, published in The Lancet medical journal, shows Ireland is on course to be one of the most obese countries in Europe by 2025.
It shows that Ireland will have the greatest number of obese men, along with Britain and Lithuania and the second highest proportion of obese women in Europe within a decade.
Ireland is one of six high-income, English-speaking countries with one-fifth of the world’s obese adults. The other countries are Australia, Canada, New Zealand, Britain and the US.
The research was conducted by scientists from Imperial College London and compared body mass index among almost 20m adult men and women from 1975 to 2014.
The institute is the only professional body for qualified dietitians in Ireland. It said people should be encouraged to eat balanced meals and a wide variety of foods.
“Managing your weight successfully means making realistic changes to your lifestyle that you can maintain. Quick fixes, like herbal supplements and fad diets, don’t work in the long term,” said Ms Reynolds.
“It’s about how much you eat as well as what you eat. Eating smaller portions will make a difference to your weight,” she said.
People needing to lose weight should aim for a 0.5kg to 1kg weight loss per week. This was a safe rate of weight loss.
“Take regular exercise. 250 minutes of moderate- intensity exercise each week is recommended to lose weight,” said Ms Reynolds.
Safefood’s director of human health and nutrition, Cliodhna Foley-Nolan said the study was “another confirmation” of the huge challenge posed by the levels of obesity to the country’s health system.
She said 90% of Type 2 diabetes and over 30% of cancers were linked with being overweight or obese.
“We also know from our own Safefood research that the economic cost of obesity, estimated at over €1.6bn, will escalate unless an urgent and comprehensive response is taken,” she said.
“Changes in personal behaviours, as well as policy measures, are urgently needed for the health of our population,” she said.
The Royal College of Physicians of Ireland’s policy group on obesity said public health policies must be an intrinsic part of the next Programme for Government. The group’s chair, Donal O’Shea, said he hoped the next government would follow Britain in introducing a sugar tax.
All four main political parties had promised to introduce the tax.
“It can’t come a moment too soon as we continue to battle high rates of obesity. One in four children in Ireland is overweight or obese,” said Prof O’Shea.